,x. . 91,; :1... .3... .. :. , . . ... . . A; . u: g... . . . . g s. n... V , .V .2. I 3.12;"..4: e: .,. ' £290 0’: dun-:23; “:‘L‘f ' 1‘ ~ ‘I u... y, _ -31 h} .‘v.-;~:b.a,§;:‘(.:" v 5 . 99.12%.th :Mwi. :% ‘9. i .33. .. ix: :5; Lu}. .J x. i Mi». . ... ,n, 3v: xmuéé $1: .71: 5% THESiS :2. "ii-a fiL’.‘ LIBRARY Michigan State University This is to certify that the thesis entitled THE EFFECT OF RELATIVE HUMIDITY ON PERMEABILITY OF ETHYL ACETATE THROUGH POLYAMIDE FILMS AT 60°C presented by Uruchaya Sonchaeng has been accepted towards fulfillment of the requirements for Master41egee in Packgging S) 07/ [C flKA/JF Major profeslor d . Date L7/02 «(OJ/@1090 I 7 0-7639 MS U is an Affirmative Action/Equal Opportunity Institution PLACE iN RETURN BOX to remove this checkout from your record. To AVOID FINES return on or before date due. MAY BE RECALLED with earlier due date if requested. DAIEEDUE DATE DUE ' DATE DUE A R 1'7 2006 AUG 1 2 2014 (- - ( 11/00 c1CIRC/DaioOuop65-p.“ THE EFFECT OF RELATIVE HUMIDITY ON PERMEABILITY OF ETHYL ACETATE THROUGH POLYAMIDE FILMS AT 60°C By Uruchaya Sonchaeng A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE School of Packaging 2000 ABSTRACT THE EFFECT OF RELATIVE HUMIDITY ON PERMEABILITY OF ETHYL ACETATE THROUGH POLYAMIDE FILMS AT 60°C By Uruchaya Sonchaeng The effect of relative humidity on the permeability of ethyl acetate vapor through a series of nylon films was studied by an isostatic procedure using the Aromatran® 1A organic vapor permeability test system. A semicrystalline nylon 6 film, an amorphous nylon (nylon 6|l6T) film and a film made from a blend of nylon 6 and nylon 6|l6T were tested at different relative humidity conditions and 60°C. The results showed ascending trends for permeability, diffusion, and solubility coefficient values as relative humidity increased. The moisture dependent properties of nylon films were also evaluated from the equilibrium moisture sorption isotherm and differential scanning calorimetry analysis. All nylon films exhibited upward trends in moisture sorption isotherms as relative humidity increased. The glass transition temperatures of the respective nylon films decreased as the amount of sorbed moisture increased. However, there was no effect of moisture on the melting temperatures and degree of crystallinity. The consistency test of the permeation data performed in this study suggested that the experimental parameters were well controlled at low relative humidity levels but deviated highly from the theoretical values at high relative humidity conditions. To my dear family and friends ACKNOWLEDGMENTS I would like to thank Dr. Jack Giacin, my major advisor, for his endless support and valuable advice throughout the duration of this research. I would also like to thank Dr. Ruben Hernandez and Dr. Randolph Beaudry for their precious comments, as well as for serving as my committee advisors. I also appreciate help from Mr. Michael Rich, Director of the Composite Center, Michigan State University, and Mr. Jim Hargreves from Modern Control, Inc. Special thanks are also for faculty, staff, and students in the School of Packaging for their support. Any remaining mistakes in this thesis, however, remain my own. TABLE OF CONTENTS ACKNOWLEDGMENTS ................................................................................................ lV TABLE OF CONTENTS ................................................................................................. V LIST OF TABLES ........................................................................................................ VllI LIST OF FIGURES ......................................................................................................... X INTRODUCTION ............................................................................................................. 1 LITERATURE REVIEW ................................................................................................... 3 1. Nylons ..................................................................................................................... 3 2. Properties of Nylons ................................................................................................ 5 2.1. Crystallinity ....................................................................................................... 5 2.2. Transition Temperatures ................................................................................... 7 2.3. Effect of Humidity ............................................................................................. 8 3. Differential Scanning Calorimetry (DSC) .................................................................. 9 4. Polymer Blends ..................................................................................................... 11 4.1. Compatibility and Miscibility of Polymer Blends .............................................. 11 4.2. Blends of Crystalline and Amorphous Nylons ................................................. 13 5. Permeability Concepts ........................................................................................... 14 6. Factors Affecting Permeability ............................................................................... 16 6.1. Nature of Polymer ........................................................................................... 16 6.2. Nature of Permeant ........................................................................................ 17 6.3. Temperature ................................................................................................... 18 6.4. Humidity ......................................................................................................... 18 6.5. Other Factors .................................................................................................. 20 7. Organic Vapor Permeability Measurement ............................................................ 20 7.1. Aromatran® 1A Organic Vapor Permeability Test System .............................. 21 V 8. Estimation of Diffusion Coefficient from Permeability Data .................................... 24 8.1. Numerical Consistency of Permeation Data .................................................... 25 MATERIALS AND METHODS ....................................................................................... 27 1. Polymer Films ........................................................................................................ 27 2. Equilibrium Moisture Sorption lsothenn ................................................................. 27 3. Differential Scanning Calorimetry (DSC) ................................................................ 28 4. Ethyl Acetate Vapor Permeability .......................................................................... 29 RESULTS AND DISCUSSION ...................................................................................... 32 1. Moisture Sorption lsotherm .................................................................................... 32 1.1. Initial Moisture Content ................................................................................... 32 1.2. Equilibrium Sorption Isothenn ......................................................................... 33 2. Differential Scanning Calorimetry (DSC) Results ................................................... 39 2.1. Glass Transition Temperature ........................................................................ 39 2.2. Melting Temperature ....................................................................................... 39 2.3. Melting Enthalpy and Degree of Crystallinity ................................................... 41 3. Ethyl Acetate Permeability ..................................................................................... 44 3.1. Transmission Rate Profiles ............................................................................. 44 3.2. Permeability Coefficient (P) ............................................................................ 51 3.3. Estimation of Diffusion Coefficient (D) and Consistency Test .......................... 55 3.4. Solubility‘Coefficient (S) .................................................................................. 60 CONCLUSIONS ............................................................................................................ 63 FURTHER STUDIES ..................................................................................................... 65 APPENDICES ............................................................................................................... 66 APPENDIX A ............................................................................................................. 67 APPENDIX B ............................................................................................................. 68 APPENDIX C ............................................................................................................ 69 vi APPENDIX D ............................................................................................................ 73 APPENDIX E ............................................................................................................. 76 APPENDIX F ............................................................................................................. 79 APPENDIX G ............................................................................................................ 81 APPENDIX H ............................................................................................................ 83 BIBLIOGRAPHY ......................................................................................................... 112 vii LIST OF TABLES Table 1. Initial moisture contents of nylon films ............................................................. 32 Table 2. 1 values for nylon films at various temperatures. ............................................. 38 Table 3. Melting temperatures of nylon films pre-equilibrated under various relative humidity conditions ................................................................................................ 41 Table 4. Melt enthalpy and percent crystallinity of Nylon 6 and Blend films pre- equilibrated under various relative humidity conditions .......................................... 44 Table 5. Permeability coefficients of nylon films at 60°C, and ethyl acetate vapor pressure of 24.36 mmHg. ...................................................................................... 53 Table 6. Estimated diffusion coefficients and parameters for consistency test of Nylon 6 film ............... . ......................................................................................................... 56 Table 7. Estimated diffusion coefficients and parameters for consistency test of Blend film ........................................................................................................................ 57 Table 8. Estimated diffusion coefficients and parameters for consistency test of Selar PA film ................................................................................................................... 58 Table 9. Solubility coefficients of nylon films at 60°C, and ethyl acetate vapor pressure of 24.36 mmHg. ..................................................................................................... 61 Table 10. Relative humidity of air over saturated aqueous salt solutions at 60°C .......... 68 Table 11. Initial moisture content of nylon films determined by Karl Fisher method ...... 69 Table 12. Initial moisture content of nylon films determined by gravimetric method ...... 69 Table 13. Initial moisture content data of Blend film determined by gravimetric method70 Table 14. Initial moisture content data of Selar PA film determined by gravimetric method .................................................................................................................. 70 Table 15. t-test for initial moisture content of Nylon 6 film determined by Karl Fisher and gravimetric methods, at the 95 percent confidence level ........................................ 71 viii Table 16. t-test for initial moisture content of Blend film determined by Karl Fisher and gravimetric methods, at the 95 percent confidence level ........................................ 71 Table 17. t-test for initial moisture content of Selar PA film determined by Karl Fisher and gravimetric methods, at the 95 percent confidence level ................................. 72 Table 18. Equilibrium moisture content data of Nylon 6 film determined at 60°C .......... 73 Table 19. Equilibrium moisture content data of Blend film determined at 60°C ............. 74 Table 20. Equilibrium moisture content data of Selar PA film determined at 60°C ........ 75 Table 21. DSC data of Nylon 6 film .............................................................................. 79 Table 22. DSC data of Blend film ................................................................................. 79 Table 23. DSC data of Selar PA film ............................................................................ 79 Table 24. t-test for melting points of Nylon 6 and Blend films determined by DSC analysis at the 95 percent confidence level ............................................................ 80 Table 25. t-test for percent crystallinity of Nylon 6 and Blend films determined by DSC analysis at the 95 percent confidence level ............................................................ 80 Table 26. Data for permeability of 24.36 mmHg ethyl acetate vapor through Nylon 6 film, at various relative humidity conditions and 60°C .................................................... 81 Table 27. Data for permeability of 24.36 mmHg ethyl acetate vapor through Blend film, at various relative humidity conditions and 60°C .................................................... 81 Table 28. Data for permeability of 24.36 mmHg ethyl acetate vapor through Selar PA film, at various relative humidity conditions and 60°C ............................................ 82 LIST OF FIGURES Figure 1. Amorphous nylon (nylon 6|l6T) ......................................................................... 5 Figure 2. Heat flow signals from MDSC: Quenched PET sample .................................. 10 Figure 3. Schematic flow diagram of the Aromatran® 1A organic vapor permeability test system ................................................................................................................... 22 Figure 4. Moisture sorption isotherms of nylon films at 60°C ......................................... 34 Figure 5. Moisture sorption isotherms of Nylon 6 at various temperatures ..................... 35 Figure 6. Moisture sorption isotherms of Selar PA at various temperatures ................... 36 Figure 7. Glass transition temperatures of nylon films as a function of relative humidity 40 Figure 8. Illustrative example of MDSC application ....................................................... 43 Figure 9. Transmission rate profile curves of ethyl acetate vapor (24.36 mmHg) through Nylon 6 film at various relative humidity conditions and 60°C ................................ 45 Figure 10. Transmission rate profile curves of ethyl acetate vapor (24.36 mmHg) through Blend film at various relative humidity conditions and 60°C ................................... 46 Figure 11. Transmission rate profile curves of ethyl acetate vapor (24.36 mmHg) through Selar PA film at various relative humidity conditions and 60°C .............................. 47 Figure 12. Transmission rate profile curves of ethyl acetate vapor (24.36 mmHg) through Nylon 6 film at various relative humidity conditions and 60°C ................................ 48 Figure 13. Transmission rate profile curves of ethyl acetate vapor (24.36 mmHg) through Blend film at various relative humidity conditions and 60°C ................................... 49 Figure 14. Transmission rate profile curves of ethyl acetate vapor (24.36 mmHg) through Selar PA film at various relative humidity conditions and 60°C .............................. 50 Figure 15. Effect of relative humidity to permeability coefficients of nylon films at 60°C, ethyl acetate vapor pressure 24.36 mmHg ............................................................ 52 Figure 16. Effect of relative humidity to diffusion coefficients of nylon films at 60°C, ethyl acetate vapor pressure 24.36 mmHg ..................................................................... 59 Figure 17. Effect of relative humidity to solubility coefficients of nylon films at 60°C, ethyl acetate vapor pressure 24.36 mmHg ..................................................................... 62 xi INTRODUCTION One important factor in the stability and shelf life of food products is the transport properties of organic vapors through the packages. The gain of off-odors or loss of specific aroma constituents through packaging materials can result in product quality loss. The wide use of polymeric materials has necessitated a search for increased knowledge of their barrier characteristics. Among commercially available polymeric materials, nylons or polyamides are well known for their high barrier properties to aromas. A major consideration for using these films as a barrier, however, is that the presence of moisture can markedly affect their barrier properties. In contrast to a number of experiments that have been performed to determine the effect of moisture on the permeability of non-interactive gases through nylon films, there exists a limited amount of data on the transport properties of organic permeants in nylons, in the presence and absence of sorbed moisture. In the present study, the permeability of ethyl acetate vapor through a series of nylon films was determined under various relative humidity conditions. The nylon films used were a semicrystalline nylon 6, an amorphous nylon (nylon 6|l6T), and a blend of nylon 6 and nylon 6|l6T. In order to predict moisture dependent properties of nylons, the water sorption isotherm of each film was also constructed. Both permeability and sorption isotherm experiments were performed at 60°C. Modulated differential scanning calorimetry (MDSC) was used in this study to determine the glass transition temperature (T9), melting temperature (Tm) and percent crystallinity of the film samples as a function of sorbed water. In addition to determining the permeability coefficient, the diffusion and solubility coefficients were also estimated from the permeability data. The consistency of the experimental data was also evaluated, based on the first order solution to Fick's Law (Gavara and Hernandez, 1993). The objectives of this study include: 1. To determine the effect of relative humidity on the permeability of ethyl acetate vapor through nylon films at 60°C. 2. To estimate the diffusion and solubility coefficients of a series of ethyl acetate vapor/nylon film systems and to study the effect of relative humidity on these parameters. 3. To study the effect of sorbed moisture on selected thermal and physical properties of nylon films. LITERATURE REVIEW 1. Nylons Nylons or polyamides are synthetic polymers, which feature the amide (-CONH-) group as a recurring functional unit in their chain structure. These polymers are prepared either by the condensation of a diamine with a dibasic acid, or by the polymerization of a lactam. Originally, the term nylon was a trademark for the polyamide based on hexamethylene diamine and adipic acid. Later it became a generic term for synthetic polyamides (Odian, 1991). Nylons are distinguished from one another by a numbering system based on the number of carbon atoms in the monomer chains. Nylons made from diamines and dibasic acids are designated by two numbers. Examples of these nylons are nylon 6/6, nylon 6/10, and nylon 6/12. The first number represents the number of carbon atoms of the diamine and the second number represents the number of carbon atoms of the dicarboxylic acid. H2N(CH2 ), NH2 + HOOC (CH2 )m_2COOH —> {NH(CH2 ), NHCO (CH2 ),,,_2 co++ H20 diamine dicarboxylic acid nylon-nm Nylons made from monomers containing both reaction species (e.g. nylon 11), or from lactams (e.g. nylon 6), are designated by a single number, which represents the number of carbon atoms in the monomer chain. H2 N(CH2 ),,_1COOH —+ {NH(CH2 ),,_1 CO,l + H20 amino nylon-n In general, nylons combine good thermal stability, flexibility and mechanical properties (Turbridy and Sibilia, 1986). They also offer clarity, thermoforrnability, as well as a barrier to gases, oils, fats, and aromas. However, nylons absorb moisture to varying degrees. Absorbed moisture can cause changes in properties and dimensions that must be considered in design and application (Williams, 1995). Water absorption decreases as the amide group concentration decreases and as crystallinity increases (Kohan, 1988). Nylon films have been used for the vacuum packaging of foodstuffs, for boil-in- bag packs, and the packaging of surgical equipment for steam sterilization. Due to the high melting temperatures, in a range of ZOO-300°C, of these polymers, products can be heat-sterilized or cooked inside them (Briston, 1986). For most packaging applications, nylons are combined with other materials that add moisture barrier and heat sealability, such as low-density polyethylene (LDPE), ethylene vinyl acetate (EVA), ethylene-acrylic acid (EAA), and ionomer (Turbridy and Sibilia, 1986). These films have applications in packaging foods such as vacuum-packing bacon, cheese, bologna, hot dogs and other processed meats. Nylon films can be produced by either cast-film processing or by blown-film processing. During film production, diverse degrees of crystallinity are obtained depending on the temperature-quenching rate. Nylons can be completely amorphous, semicrystalline, or almost completely crystalline. The terms crystalline and amorphous are used to indicate the ordered and unordered polymer regions, respectively, and the term semicrystalline is referred to polymers that are partially crystalline. When the cooling rate is increased, a less crystalline nylon is obtained, since the polymer is not given sufficient time to form crystals (Hernandez, 1996). The increase in amorphousness produces a more transparent and more easily therrnofonnable film. Recently, amorphous nylons have been developed and introduced. These nylons are actually copolymers containing side groups in their structure. An example of amorphous nylon is nylon 6|l6T, the nylon made from hexamethylene diamine and a 70:30 mixture of isophthalic (I) and terephthalic (T) acids (see Figure 1). This polymer was commercialized by the DuPont company (Vifilmington, DE), as Selar® PA. Since the acid isomers are randomly placed within the polymer backbone, resulting in structural irregularity, no crystallization of the polymer matrix is observed. No evidence of a crystalline melting point was found by performing differential scanning calorimetry (DSC) analysis (Blatz, 1989). COZH 002H + + NHZCH2(CZH4)ZCH2NH2—> Amorphous Nylon COZH C 2H Isophthalic Terephthalic hexamethylene acid acid diamine Figure 1. Amorphous nylon (nylon 6|l6T) Amorphous nylons are characterized by high clarity, high strength properties, a lower water absorption rate than nylon 6 and fair to good chemical resistance. The gas barrier properties of amorphous nylons fall right at the borderline between high and moderate barrier (Foster, 1991). Commercially, amorphous nylons have been used as the barrier in both monolayer and multilayer packages for specialty chemicals, cosmetics, and certain dry foods, with potential for a variety of food applications (Briston, 1 988). 2. Properties of Nylons 2.1. Crystallinity The extent of crystallinity developed in a polymer sample is a consequence of both thermodynamic and kinetic factors. Thermodynamically, crystallizable polymers generally must crystallize at reasonable rates, if crystallinity is to be employed from a practical viewpoint. The extent to which a polymer crystallizes depends on whether its structure is conducive to packing into the crystalline state and on the magnitude of the secondary forces, e.g. dispersion, dipole-dipole, and hydrogen bonding, of the polymer chains. Packing is facilitated for polymer chains that have structural regularity, compactness, and some degree of flexibility. Generally, the stronger the secondary forces, the greater will be the driving force for the ordering and crystallization of polymer chains (Odian, 1991). Usually, nylons are highly crystalline polymers. Hydrogen bonding of the polar amide group leads to strong secondary forces in nylons, which is favorable for crystallization. Crystallinity in nylons can be significantly increased by a mechanical stretching process, which facilitates the ordering and alignment of polymer chains. On the other hand, increasing the cooling rate during film production yields a less crystalline nylon. A completely amorphous nylon, such as Selar® PA, can be produced by increasing structural irregularity of the polymer backbone. In this polymer, the random placement of the acid isomers in the polymer chain prevents crystallization. Among a variety of methods, differential scanning calorimetry (DSC) has become the most popular analytical tool for determining the degree of crystallinity in polymers. The DSC method for determining the percent crystallinity of a semicrystalline polymer is based on the measurement of the heat of fusion, AH,, and the reasonable assumption that this quantity is proportional to the percent crystallinity (Wunderlich and Corrnier, 1967). The percent crystallinity may be estimated from: %Crystallinity ; 32C x 100 (1) f where AH} is the heat of fusion for a hypothetical 100% crystalline sample. The difficulty in using thermal analysis (e.g. DSC) is the uncertainty in the values of the quantity measured for 0 and 100% crystalline samples, since such samples seldom exist. The best technique is to calibrate the method with samples whose degree of crystallinity have been determined by X-ray diffraction (Odian, 1991). 2.2. Transition Temperatures Polymeric materials are characterized by two major types of transition temperatures, the crystalline melting temperature, Tm, and the glass transition temperature, T9. The crystalline melting temperature is the melting temperature of the crystalline domains of a polymer sample. The glass transition temperature is the onset temperature above which free vibrational and rotational mobilities of polymer chains occur, so that different chain conformations can be assumed. Whether a polymer sample exhibits both thermal transitions, or only one, depends on its morphology. A completely crystalline polymer shows only a Tm, while a completely amorphous polymer shows only a T9. Semicrystalline polymers exhibit both crystalline melting and glass transition temperatures. The two thermal transitions are generally affected in the same manner by the molecular symmetry, structural rigidity, and secondary forces of polymer chains (Billmeyer, 1984; Mark et al.,1984; Sperling, 1986; Williams, 1971). The values of Tm and T9 for a polymer affect its properties, at any particular temperature, and determine the temperature range in which that polymer can be employed. Generally, the glass transition temperatures of aliphatic nylons appear to be below room temperature so that the materials have a measure of flexibility, in spite of their high crystallinity, under general conditions of service (Brydson, 1982). In contrast to semicrystalline nylons, the amorphous nylons typically have higher glass transition temperatures and exhibit higher levels of stiffness (Torre, 1995). The transition temperatures of nylon 6 and amorphous nylon have been examined by Blatz (1989). Using a thermal analysis technique, the author reported that nylon 6 has a Tm of 222°C and a T9 of 39°C and amorphous nylon has a T9 of 125°C. 2.3. Effect of Humidity For nylons, hydrogen bonding between adjacent amide groups of polymer chain segments is a major contributor to intermolecular cohesion. Disruption of such intermolecular hydrogen bonding is necessary for a solvent such as water vapor to attack nylons, and is a major factor in the mechanism of absorption of moisture by such polymers (Kohan, 1988). The absorbed moisture weakens the intermolecular forces in the polymer chain, resulting in a plasticized polymer matrix, thereby reducing the glass transition temperature of the polymer. The reduction in T9 is proportional to the amount of water absorbed (Jabarin and Lofgren, 1986; Sfirakis and Rogers, 1980). Due to this plasticizing effect of water, the properties of nylons are strongly dependent on the moisture content of the polymer. A number of studies have described the effect of sorbed water on the physical and mechanical properties of nylon films. Blatz (1989) and Hernandez et al. (1992) reported that the sorption of water significantly decreases the T9 of amorphous nylon from 125°C at dry conditions to 50°C as 8% of water is sorbed in the film. In a similar fashion, the sorption of water by nylon 6 reduces its Tg from 50°C at dry conditions to -20°C with 6% of moisture sorbed (Khanna et al., 1995). The density, after immersion in water, of amorphous nylon shows a distinctive increase, as opposed to an expected decrease based on the addition of a lower density material. The density increase is related to the occupation of free volume in the polymer by sorbed water (Khanna et al., 1997). 3. Differential Scanning Calorimetry (DSC) Differential scanning calorimetry (DSC) has become the most popular analytical tool for determining transition temperatures, as well as the degree of crystallinity. DSC is a technique of nonequilibrium calorimetry in which the heat flow into or away from the test sample is measured as a function of temperature or time (TA Instruments, 1998a). Presently available DSC equipment measures the heat flow by maintaining a thermal balance between the reference and sample, by changing the current passing through the heaters under the two chambers. For instance, the heating of a sample and reference proceeds at a predetermined rate, until heat is emitted or consumed by the sample. If an endothermic occurrence takes place, the temperature of the sample will be less than that of the reference. The circuitry is programmed to give a constant temperature for both the reference and the sample compartments. Excess current is therefore fed into the sample compartment to raise the temperature to that of the reference. The current necessary to maintain a constant temperature between the sample and reference is then recorded (Seymour and Carraher, 1992). DSC has many advantages which contribute to its widespread usage, including fast analysis time, easy sample preparation, applicability to solids and liquids, a wide temperature range, and excellent quantitative capability. On the other hand, DSC has some limitations. In order of importance, these limitations are the ability to properly analyze complex transitions, the presence of sufficient sensitivity, the presence of adequate resolution, and the need for complex experiments (TA Instruments, 1998b). Modulated DSCTM (MDSC) is an extension to conventional DSC. It is used to study the same material property changes which are evaluated by conventional DSC, including: (i) transition temperatures; (ii) melting and crystallization; and (iii) heat capacity. However, in MDSC, a rapid heating rate oscillation is added to a conventional 66.8 c. 36965 2.26:0 2 camp: mEb . 389 95828:. (.5 anmm Fwd 365:0 HOwe.)— Eo: £29m 26: “no: .N 9:9". Gov 929an2. a: 90 com . omw com om? 2.: on .. -80- r v r .o- m r .o- l . r omd- 1 mo olll\ (I 9.7.551 . . H 8.0 - . m 1 No.0- rmo O- H - (ll. m .28. . ) m [3.0 not m r .o l I ofio 33.05302 . r o F .o . .. mad omd l .. 9.0 . 10 linear temperature ramp or timed isothermal period. Then a Fourier transform deconvolution process is used to separate the resultant total heat flow signal into reversing and non-reversing components (Figure 2). Events observed in the reversing heat flow are usually transitions which are thermodynamically reversible at the time and temperature at which they are detected. Typical reversing events are glass transitions and melting of polymers. Conversely, nonreversing events are usually thermodynamically nonreversible at the time and temperature at which they are detected. Examples include enthalpic relaxations, cold crystallization, evaporation, thennoset cure, and decompsition (TA Instruments, 1998b). 4. Polymer Blends Polymer blends, often referred to by the contraction polyblends, are a mixture of different polymers on a molecular level (Seymour and Carraher, 1992). A primary reason for blending polymers is a practical one of achieving commercially viable products through either unique properties or lower cost than some other means might provide (Paul at al., 1988). There is considerable activity in this area since polymer blends can be used to combine the properties of different polymers. New products can be obtained and markets expanded by the physical mixing together of existing products without the need to synthesize a new polymer (Odian, 1991). 4.1. Compatibility and Miscibility of Polymer Blends A major concern for polymer blends is the compatibility of the polymers. The compatibility of blend components refers to the level of homogeneity the polymer- polymer mixture exhibits on a macroscopic scale, as well as interactions at the microscopic level (Kienzle, 1988). For example, a visibly heterogeneous mixture would be described as incompatible. Compatible blends, on the other hand, appear homogeneous on a macroscopic level. 11 On a microscopic level, the compatibility of the blend is best described by the miscibility of the polymers, or the level of intermingling between polymer constituents (Kienzle, 1988; Krause, 1978). The miscibility or immiscibility of two polymers is determined by the thermodynamics of the mixture (Paul, 1978), as expressed by the free energy of mixing expression: AGWX = AHmb, — TASmb, (2) For miscibility, the free energy of mixing, AGmix, must be negative. Although the change in entropy of mixing, ASmix, is positive and favors miscibility, the change is very small because of the small number of moles of each polymer in the blend. In addition, mixing is usually an endothermic process and the enthalpic change, AHmix, is expected to be positive. Thus, most polymers are immiscible. However, the enthalpy of mixing can be negative, or exothermic, if certain specific interactions are involved, and consequently 216”"), will be negative in spite of the small entropy. These interactions may arise from a variety of mechanisms, such as dipole-dipole forces, hydrogen bondings, or intramolecular repulsions (Paul, 1978). From the above discussion, there are three possible morphologies of polymer- polymer mixtures, which are miscible, partially miscible, and immiscible (Fox and Allen, 1985). A miscible polymer blend exhibits strong attraction between its polymer constituents, generally arising from interactions between functional groups of the polymers. The miscible polymer-polymer combination has a single phase and a single T9. Partially miscible polymer combinations display some miscibility. The partial miscibility improves adhesion at the interface of the two polymers, resulting in generally good physical and mechanical properties. Immiscible blends exhibit limited attraction between polymer constituents, while the component polymers exist as two phases. The 12 polymer present in the higher concentration forms the continuous phase. The constituent of lower concentration forms a dispersed phase. Miscible blends are optically clear and have good mechanical integrity, whereas immiscible blends are usually translucent or opaque and weak (MacKnight et al., 1978). However, immiscible polymer blends can be transparent in some cases, such as when the two components have equal refractive indices (MacKnight et al., 1978). A more reliable criterion of a miscible polymer is the detection of a single T9, which exhibits a temperature intermediate between those corresponding component polymers (Harris and Merriam, 1988). At the other extreme, blends of immiscible polymers that segregate into distinct phases exhibit glass transitions identical in temperature and width to those of the unblended components. In intermediate cases, partially miscible blends of two polymers have two distinct Tg values, both of which are between the T,I values of the constituent polymers (Kienzle, 1988). 4.2. Blends of Crystalline and Amorphous Nylons Semicrystalline nylons such as nylon 6, when used as films, offer good physical strength, good chemical resistance, and moderate barrier properties. Films from amorphous nylons have excellent optical and barrier properties, but lack the toughness and mechanical durability of crystalline nylon. Blending of these two nylons in a specific composition range can provide unusual mechanical properties, along with good optical and barrier properties (Blatz, 1989). The barrier properties of the blends fall between the perfonnanCe of nylon 6 and amorphous nylon. However, as the humidity increases, adding even small amount of amorphous nylon improves the barrier more than would be predicted by a straight-line regression (DuPont, 1996b). The T9 and the level of crystallinity of the film blends have been studied by Blatz (1989). The results have shown that blends of nylon 6 and amorphous nylon are 13 compatible, since only one T9 is detected. The T9 of the blends shows a dramatic decrease as the amount of nylon 6 increases. The crystallinity is significantly decreased by minor amounts of the amorphous component. It was also found by Blatz (1989) that the addition of amorphous nylon to nylon 6 not only reduces the amount of crystallinity of the resultant polymer blend, but also reduces the melting point and broadens the melting endotherm. Such a drop in melting point can be the result of the diluent effect of the amorphous component, as the amorphous component is reluctant to crystallize (MacKnight et al., 1978). 5. Permeability Concepts Permeability is the phenomenon of transmission of a gas or vapor through a polymer. It concerns a mass transfer process appropriately known as permeation and is associated with a partial pressure differential of a gas or vapor between the two sides of a film or sheet (Miltz, 1992). Permeation is commonly regarded as consisting of three processes (Stannett and Yasuda, 1965): (i) absorption and solution of the permeant into the polymer matrix at the high permeant concentration surface; (ii) diffusion of permeant through the polymer wall along a concentration gradient and toward the low concentration side; and (iii) desorption or evaporation of the permeant from the surface at the lower concentration. The diffusion flow or flux density (F) of a permeant through polymer film is defined as the amount of permeant passing through a surface of unit area normal to the direction of flow during unit time, as described by equation (3). F=9 (3) At 14 where Q is the total amount of permeant, A is area, and tis time. The relationship between the flux F and the concentration gradient is described by Fick's First Law (Crank, 1975): F = —D 9'3 (4) dx where D is the diffusion coefficient, and dc/dx is the concentration gradient in the direction of flow. From a mass balance standpoint, assuming that diffusion takes place only in the x direction, Fick's Second Law is derived (Meares, 1965): 2 92-09.; dt dx (5) where t is time. When the diffusion process reaches the steady state, F reaches a constant value, if the permeant concentration at both sides of the film, a, and C2, are maintained constant. Equation (4) can then be integrated across the total thickness of the film L, independent of concentration, thus: =D(Cr-Cz) L F (6) By substituting for F using Equation (3): _ 0(c, — c2 )At Q L (7) When the permeant is a gas, it is more convenient to measure the vapor pressure p, which is at equilibrium with the polymer, rather than the actual concentration c, that is the concentration of permeant within the polymer. At sufficiently low concentrations, Henry's Law applies and c can be expressed as: c = Sp (3) 15 where S is the solubility coefficient of the permeant in the polymer. Consequently: Q = DSIP1ZP2MI (9) Rearranging equation (9): 3=___g-____ At(p1 ‘p2) (10) where P is the permeability coefficient. The permeability coefficient P can be determined from direct measurement of the transmission rate of a gas through a polymer or from the relationship of P = 08 where D and S are separately determined (Crank and Park, 1968). 6. Factors Affecting Permeability Permeability is affected by several factors, some of which are dependent on the properties of the polymer, some controlled by the properties of the permeant, and others by the environmental conditions. 6.1. Nature of Polymer The chemical nature of the constitutional unit of a polymer is one important factor that determines the polymer permeability. Chemical composition, polarity, stiffness of the polymer chains, bulkiness of side— and backbone-chain groups, and the degree of crystallinity significantly impact the sorption and diffusion of a permeant (Hernandez, 1996). Generally, polymers with glass transition temperatures above room temperature have very stiff chains and low gas permeability. There are some exceptions, especially if the polymer also has a high free volume (Salame, 1986). The free volume of a 16 polymer is the molecular void volume that is trapped in the solid state. The permeating molecule finds an easy path through these voids. In general, a polymer with poor symmetry in the structure, or bulky side chains, will have high free volume and high permeability. Certain polymers can have varying degrees of crystallinity. A higher degree of crystallinity, within the same generic class of polymer, usually affords a better barrier, since the permeant cannot penetrate or diffuse through a polymer crystallite. However, some transparent polymers, with very low or nonexistent crystallinity, exhibit better barrier properties than semicrystalline polymers. For instance, an amorphous nylon fllm, Selar® PA, is a better barrier against oxygen than semicrystalline nylon 6 (DuPont, 1996b). Moreover, the effect of crystallinity can hardly be discussed, independent of that of sorbed water. Blatz (1989) reported that exposing the film from blends of amorphous nylon and semicrystalline nylon 6 to high humidity resulted in further crystallization of the film. This effect was indicated by the differences in the crystallization exotherrns, obtained from DSC analysis, of dry and humidified film samples. 6.2. Nature of Permeant As indicated above, the composition and molecular structure of the polymer can play an important part in determining the permeability of a barrier material. Likewise, the molecular structure of the permeant is of importance in the following manner. An increase in the size of a permeant generally leads to an increase in the solubility coefficient and a decrease in the diffusion coefficient. Since the permeability coefficient is the product of these, its variation with permeant size is often much less (Rogers, 1985). The elongated or flattened molecules diffuse faster than spherical ones of similar volume or molecular weight. This implies that anisotropic molecules are oriented and move along their long dimension during diffusion (Berens and Hopfenberg, 1982). 17 The permeation of more condensable vapors and liquids through a polymer membrane usually proceeds at much greater rates than does the permeation of gases. Good solvents swell and plasticize the polymeric structure, which leads to increased mobilities of both polymer chain segments and permeant molecules (Rogers, 1985). 6.3. Temperature Permeability, diffusion, and solubility coefficients are affected by temperature following the Arrhenius relationships, as given in Equations (11), (12), and (13). D = 0., exp(— Ed / RT) (11) s = 30 exp(AHs / RT) (12) P = P0 exp(——Ep / RT) (13) where D,,, So, and P0 are constants, Ed is the activation energy for diffusion, AHs is the heat of solution, [5,, is the activation energy for permeation (i.e. Ed-I-AHS), T is the absolute temperature, and R is the universal gas constant. The above equations can be used to estimate the permeability coefficient at a desired temperature from a known value. However, they are valid over a relatively small range of temperatures, which should not include the glass transition temperature of polymers. In particular for P, polymers show higher values of Ep, at temperatures above Tg than below Tg (Hernandez, 1996). Consequently, the permeability of a polymer membrane is higher at a temperature above Tg than at a temperature below T9. This effect can be described by the increases in polymer chain segmental mobility above the glass transition temperature, which corresponds with an increase in permeability and diffusion. 6.4. Humidity Hydrophilicpolymers such as nylons can sorb moisture from the atmosphere. The presence of water in a hydrophilic polymer affects the permeability of gases and 18 vapors. If water swells or plasticizes the polymer chains, the gas permeation can be increased (Ito, 1961; Salame, 1986). This effect is due to the greater ease of polymer chain segmental mobility (Crank and Park, 1968), which results in an increased gas diffusion rate and greater sorption capacity of the polymer matrix (Lim et al., 1998). The effect of relative humidity on the permeability of non-interactive gases through nylons has been studied in considerable detail. Simn’l and Hershberger (1944) reported increases in the permeability of oxygen, nitrogen and carbon dioxide through nylon films, as the relative humidity increases. Meyer et al. (1957) and Ito (1961) also found similar results for the permeability of carbon dioxide through nylon 6. Recently, as modern test systems have been developed, the oxygen permeability of nylon 6 has been re-examined (Hernandez, 1994; Khanna et al., 1997; Ohashi, 1991). Such studies revealed that oxygen permeability of nylon 6 exhibits a minimum at about 30-35% RH and then increases at higher relative humidity values. The trend of a decrease in oxygen permeability with increasing relative humidity is usually not found with most commercial oxygen barrier materials. However, it appears to be a general feature in amorphous polyamides, such as Selar® PA (DuPont, 1996a; Hernandez, 1989; 1994), and polyimide films (Chern et al., 1983; Pye et al., 1976). This phenomenon is caused by the filling up of the free volume voids by water molecules, thus making them inaccessible to diffusion by the permeating gas or vapor. Providing the water sorbed is not sufficient to plasticize the polymer, permeation of oxygen will decrease (Salame, 1986). In contrast to the amount of data in the literatures on the permeability of non- interactive gases, there exists a limited amount of data on the transport properties of organic permeants through nylons as a function of relative humidity. Nagaraj (1991) reported that the sorption of water vapor by an amorphous nylon (Nylon 6|l6T) resulted in an increase in the permeability coefficient values for acetone vapor, as compared to 19 dry conditions. Lim (1998) studied the permeability of allyl isothiocyanate (AIT) vapor in nylon 6,6 film, as a function of sorbed water, and found that AIT permeability increased exponentially with relative humidity. 6.5. Other Factors Chain orientation, permeant concentration, fillers, and plasticizers can affect the permeability of polymer membranes. Chain orientation normally decreases the permeability to gases (Salame, 1986). However, in practice, orientation also introduces mechanical strains or defects resulting from stretching a rigid crystalline film and can cause an increase in permeability as well (Khanna et al., 1997). The concentration of permanent gases such as oxygen and carbon dioxide, below one atmosphere of pressure, in general does not affect the permeability coefficient. However, strong concentration effects have been observed in the permeability of organic compounds (Liu, 1986; Meares, 1965). The use of inert fillers in polymers can either increase or decrease permeability, depending on the degree of compatibility and adhesion between the polymer matrix and filler. For instance, the oxygen permeability of low density polyethylene (LDPE) film decreases when surface-treated calcium carbonate filler is added. In contrast, untreated calcium carbonate at the same concentration increases the oxygen permeability of LDPE film (Nemphos et al., 1986). Some additives incorporated into polymers, such as plasticizers, usually increases permeation, depending on the system (Ashley, 1985). 7. Organic Vapor Permeability Measurement There are various methods for measuring permeability, which differ in terms of procedure and apparatus. In general, there are two basic test methods, which are referred to as the isostatic and quasi-isostatic methods (Hernandez et al., 1986). In an isostatic method, the transport of a permeant through a polymer membrane is continually 20 monitored. In a quasi-isostatic method, the amount of a permeant that has passed through the film and accumulated is monitored as a function of time. Studies on organic vapor permeability by both methods have been described by a number of investigators (Baner et al., 1986; DeLassus et al., 1988; Gilbert et al., 1983; Hernandez et al., 1986; Huang and Giacin, 1998; Liu et al., 1991; Niebergall et al., 1978; Pye et al., 1976; Sajiki and Giacin, 1993; Zobel, 1982). However, since the measurement of organic vapor permeability is quite complicated, researchers usually designed their own systems to perform organic vapor permeability studies. Test results obtained from these systems may vary from laboratory to laboratory, depending on the variation of the equipment and the experience levels of the operators. There had been no test standard for organic vapor permeability measurement until the standard test method ASTM F1769 was adopted in 1997. This test method covers the measurement of the barrier properties of films, plastic sheeting, coated papers, and laminates to volatile organic vapors. The apparatus required in this standard is based on an isostatic procedure, utilizing a flame ionization detector (FID) for quantification. Therefore, the test vapors to be used are limited to those volatile organic compounds, which are detectable by a FlD. The specific material properties, which are diffusivity, solubility, and permeability coefficients, can be determined using Fick's Laws and the application of Henry's Law. In response to the demand for a better and more precise instrument, several organic vapor permeability test systems have been introduced recently. An example of such a commercial unit is the Aromatran® 1A (Modern Control, Inc., Minneapolis, MN) organic vapor permeability test system. 7.1. Aromatran® 1A Organic Vapor Permeability Test System Based on the isostatic method, the Aromatran® 1A is designed to test a single permeant under dry or at specified relative humidity conditions, with the test temperature 21 .Aommr .ZOOOs: Em~m>m 68. §=nmoEod Loam> 2:35 3 GammeoZ 05 Lo E986 26: 2589.8 .m 939“. 533.53 9% 5.me V A . 3< ._ 2. $819: w > 20m}; Eon m>._<> 30.7. 2. m_< m>.._<> "7.920 _ 5.9.3wa OKMN m>4<> HwD4<> mwogmw Z_ ZNGOKH>Z wZ $5,; 26.: «mags; 20 5m: 96 mek 22 ranging from 5 to 65°C. The test unit is incorporated with a flame ionization detector (FID), temperature controller, barometer, flow meter, and relative humidity sensors, making the testing system well controlled under desired test conditions. Figure 3 presents the schematic diagram of the Aromatran® 1A. The test gas to be used in the Aromatran® 1A can be a certified gas or a sparging gas. In the case of a sparging gas, a temperature controller bath is employed to control the temperature of the liquid permeant in the sparger. The carrier gas, usually nitrogen, is then passed through the liquid permeant in such a manner so as to obtain a fixed and stable saturation vapor pressure of the permeant in the test gas stream. The test gas stream is connected directly to the test gas input port of the Aromatran® 1A. To generate the precise relative humidity conditions, the generated RH method (Demorest and Mayer, 1996) is utilized. This method enables the operator to create the desired relative humidity by adjusting the gas pressure, as it passes over a distilled water humidifier. It is important to calibrate the system with the permeant to be used prior to conducting permeability experiments. In addition, it is also recommended that the system should be re-calibrated whenever the test conditions (i.e. temperature and relative humidity) are changed. The calibration of the Aromatran® 1A is based on the assumption that the relationship between the HO response and the organic vapor partial pressure is linear. The calibration is initiated by introducing the test gas stream of known vapor pressure directly to the FID. The detector response versus vapor pressure of the test gas is then computed and stored for further applications. To test a flat film sample, the film sample is mounted in the test cell. The test temperature and humidity of the gases are adjusted to the required values. The film is then exposed to the test gas on one side. The carrier gas, sweeping through the other side, is conveyed directly to the FID. The transmission rate profile is then monitored 23 until the steady state is reached. Once the test is completed, the values of P, D, and S can be calculated. The permeability coefficient P is calculated from the final transmission rate as expressed in Equation (10). The diffusion coefficient D can be calculated from: L2 D = —— (14) where I” is the time required at half the final transmission rate (Ziegel et al., 1969). The solubility coefficient (8) can be calculated from the relationship 8 = P/D, as P and D are known. 8. Estimation of Diffusion Coefficient from Permeability Data The estimation of diffusion coefficient (D) values requires a more detailed evaluation of Fick's First Law (Equation 4). A solution to Equation (4) was presented by Pasternak, et al. (1970), as expressed by Equation (15): F 4 L2 V2 _ nsz ._i = — — ex 15 4Dt where F, is the flux of the permeant through the film sample, F3s is the steady-state flux, M8 .0" L is the thickness of the film sample, D is the diffusion coefficient, and t is time. The above solution is subjected to the following boundary conditions: (i) the structure is initially void of permeant concentration; (ii) the film surface exposed to the test gas permeant is held at a constant concentration; and (iii) the film surface which is exposed to the detector is effectively maintained at zero concentration (Crank, 1975). The first order solution to Equation (15) is as follows: i: _4_ _ 16 F. (5117911 X) < > 24 where L2 ‘25; “7’ For each value of Ft/FSS over the transient portion of the transmission rate profile, a value of X can be calculated by a parameter estimation technique, such as the Newton-Raphson method (Gottfried, 1998), and the diffusion coefficient (D) can be obtained from the slope of a plot between 1/X versus t (Hernandez et al., 1986) as follows: 2 D = (Slope ).L 4 (18) For non-interactive permeants, permeability and diffusion data are well described by Equation (15). In this case, Henry's Law of solubility (Equation 8) applies, and D is considered independent of time and permeant concentration (Gavara and Hernandez, 1993). However, when the permeability process involves highly interactive organic penetrants such as aroma, flavor, or solvent molecules, the diffusion process is more complex, and the diffusion coefficient may vary as a function of penetrant concentration and time (Giacin and Hernandez, 1997). 8.1. Numerical Consistency of Permeation Data A numerical consistency of the permeation data obtained from isostatic permeability experiments can be performed as described by Gavara and Hernandez (1993). Based on the first order solution to Fick's Law expressed in Equation (16), the authors introduced two dimensionless constants K, and K; as defined by Equations (19) and (20), respectively: 25 K, =E2i=§921=a4405 (19) t0.75 X075 K2 = 59—21 = 5933 = 0.6681 (20) t0.5 X05 where X025, X05, and X015 denote the numerical values of X when the transmission rate ratio F,/FSS had reached values of 0.25, 0.5, and 0.75, respectively. The values of K, and K2, together with the linear relationship of 1/X versus time, are criteria to evaluate the consistency of a set of experimental permeability data (Gavara and Hernandez, 1993). The closer the calculated values of K1 and K2 to those given by equations (19) and (20) and the higher the correlation coefficient of the plot of 1/X versus time, the better the experimental data fits the ideal curve, as given by equation (15). 26 MATERIALS AND METHODS 1. Polymer Films 1) Nylon 6 film was 1.65 mil Ultramid® B36FN film (BASF Corporation, Mount Olive, NJ). This film was made from a medium viscosity, extrusion-grade nylon 6 resin, with lubricant and nucleating agent added. 2) Amorphous nylon film, also known as nylon 6|l6T, was 1.70 mil Selar® PA 3426 film (E. I. Du Pont De Nemours and Co., New Castle, DE). The film was made from an extrusion/injection-grade resin. 3) Film made from blending 90% non-nucleated nylon 6 (Ultramid® B35F, BASF Corporation, Mount Olive, NJ) and 10% Selar® PA 3426 was 1.81 mil Ultramid® 335F090 film (BASF Corporation, Mount Olive, NJ). For convenience, the nylon 6 (Ultramid® B36FN) film will be referred to as Nylon 6, the amorphous nylon film as Selar PA, and the Ultramid® B35FQ90 film as Blend. 2. Equilibrium Moisture Sorption Isotherrn The initial moisture content (IMC) of each film sample was determined by two methods, Karl Fischer and gravimetric. For the Karl Fischer method, the Metrohm volumetric Karl Fischer titrator model 720 (Metrohm Ltd., Herisau, Switzerland) was used for moisture content determination. Initially, a mixture of Karl Fischer reagent (Riedel-de Haén Laboratory Chemicals, Seelze, Germany) and methanol (J. T. Baker, Phillipsburg, NJ) were continually stirred in a sealed flask. A voltage reading from the reagent mixture was collected by a platinum electrode. The film sample was cut into small pieces, approximately 0.25 inch x 0.25 inch, and put into the flask through a sample port. Moisture from the sample caused changes in the voltage reading and the 27 Karl Fischer titrator automatically added reagent until the initial voltage was achieved. The moisture content was then determined from the voltage difference and the output was reported. For the gravimetric method, each sample was weighed initially and then dried in a vacuum oven at 80°C for 6 hours. The initial moisture content was then determined from the weight loss of the sample (Appendix A). The equilibrium moisture sorption isotherms developed in this study were determined gravimetrically at 60°C. Five humidity chambers were prepared by placing appropriate salt solutions (Appendix B) in tightly closed containers and were allowed to equilibrate at 60°C for at least 7 days. The range of relative humidities selected for this study was from 30 to 80 percent, which corresponded to the relative humidity range of the Aromatran® 1A organic vapor permeability test system. The relative humidities were then monitored using hygrometer sensors (Hydrodynamics Co., Silver Spring, MD). Film samples were initially weighed and then placed into each of the humidity chambers. At predetermined time intervals, the film samples were taken out of the respective humidity chambers and weighed. This procedure was repeated until a constant weight was obtained. The equilibrium moisture contents (EMC) were determined (Appendix A) and the moisture sorption isotherm of each film was then constructed. 3. Differential Scanning Calorimetry (DSC) Glass transition temperature (T9), melting temperature (Tm), and percent crystallinity of nylon film samples were determined using Modulated DSCTM (MDSC) technique. The film samples were cut into small pieces and equilibrated at 60°C in a series of humidity chambers, as explained in the previous section. The film samples were allowed to equilibrate for at least 7 days. Dry film samples were dried in a vacuum oven at 80°C for 6 hours and then equilibrated in a desiccator containing dry silica gel, at room temperature. 28 DSC analysis was performed using the DSC 2920 Differential Scanning Calorimeter (TA Instruments Inc., New Castle, DE) equipped with Modulated DSCTM cell base. The film samples of different moisture contents were sealed rapidly in DSC pans and then scanned in the DSC instrument at the heating rate of 4°Clmin from 0°C to 250°C, and modulated condition of :1°C every 60 seconds. Therrnograms were analyzed to obtain glass transition temperatures, melting temperatures and melting enthalpies by using the manufacturer's software (Universal Analysis software, TA Instruments Inc., New Castle, DE). 4. Ethyl Acetate Vapor Permeability The measurements of ethyl acetate vapor penneabllity through nylon film samples were performed on the Aromatran® 1A organic vapor permeability test system (Modern Controls Inc., Minneapolis, MN). Ethyl acetate vapor was generated by passing dry nitrogen gas through a sparging system (Figure 3) containing liquid ethyl acetate (Aldrich Chemical, Milwaukee, WI). The sparger was placed in a temperature control bath (NESLAB RTE-100 Refrigerated Bath Circulator, NESLAB Instruments Inc., Portsmouth, NH). Throughout this study, temperature of the bath was set to 0°C and nitrogen flow was set to 15 mL/min. Nitrogen gas carrying ethyl acetate vapor was then a test gas and was connected to the test gas input port of the Aromatran® 1A. Various relative humidity conditions were controlled by adjusting the pressure in the humidifier chambers. The humidifier chambers were filled with deionized water for humidified conditions and were left free of water for dry conditions. The pressures in both test gas and carrier gas humidifiers were always set to an equal value. 29 Prior to the permeability measurement, a calibration of the system had to be accomplished. Test gas and carrier gas flows were set equally to 15 mL/min. Relative humidities for the test gas and carrier gas streams were set and measured by two separate relative humidity sensors, which were attached to the test gas side and carrier gas side of the test cell, respectively. Relative humidities and flows were then monitored and adjusted to the required values. Once all parameters were set up, a calibration was initiated by introducing the test gas stream of known vapor pressure directly to the flame ionization detector (F ID). Calibration was completed when the FID output reached a constant value. To confirm the accuracy of the ethyl acetate vapor pressure measurement, samples of vapor from the test gas exhaust port were withdrawn with a gas tight syringe (Gastight® syringe #1750, Hamilton Co., Reno, NV) and injected directly into the gas chromatograph (Hewlett-Packard 5890A Gas Chromatograph, Hewlett Packard, Avondale, PA) for quantification. The vapor pressure values determined by gas chromatography were then input to the computer software, as the correct vapor pressure. The detector response versus vapor pressure of the test gas was then computed and stored in the Aromatran® 1A calibration file for further applications. The system was calibrated every time the test conditions (i.e. relative humidity and temperature) were changed, in order to compensate any fluctuation of the FID due to temperature change or moisture interference. For the test procedure, the film sample was heated in an oven at 80°C for at least 6 hours prior to each experiment to desorb any residual volatiles in the film. All flows and humidity conditions were set to the required values. The film sample was then cut with a special die and placed in the test cell. The film sample was conditioned with a carrier gas stream of specific relative humidity in the cell for at least 24 hours for dry conditions, and for at least 48 hours for humidified conditions. To initiate a test, the test 30 gas was passed through one side of the film sample. The carrier gas stream, sweeping through the other side of the film, was conveyed directly to the FID. The transmission rate profile was then computed from the FID signals utilizing the manufacturer's software. Testing was terminated by the operator when the transmission rate reached a constant value which was maintained for a period of 2 hours. Each transmission rate profile was analyzed and the permeability, diffusivity, and solubility coefficients were then calculated. 31 RESULTS AND DISCUSSION 1. Moisture Sorption lsotherrn 1.1 . Initial Moisture Content The initial moisture content (IMC) of the respective nylon films was determined by gravimetric and Karl Fisher methods. The results are presented in Table 1. Statistical analysis of the results from both methods (Appendix C) shows no significant difference for all nylon films, at the 95 percent confidence level. Table 1. Initial moisture contents of nylon films Initial moisture content (%) Sample Karl Fisher Gravimetric Nylon 6 2.74 i 0.06 2.69 i 0.08 Blend 2.88 i 0.18 2.99 i 0.04 Selar PA 2.24 i 0.23 2.50 i 0.03 Since the results from both gravimetric and Karl Fischer methods yielded no significant difference, the gravimetric method was selected for further equilibrium moisture content determinations, due to the following reasons. The film samples prepared for the Karl Fischer method were cut into small pieces in order to enhance the accuracy of moisture detection, as well as to fit the size of the small sample insertion port of the titrator. These pieces of samples frequently obstructed the reagent flow to the electrode, consequently caused unstable voltage readings. Whereas this problem could be lessened by adjusting the speed of the magnetic stirrer inside the titration flask, 32 other concerns remained. The sample pieces had to be removed and the system had to be cleaned and re-calibrated each time a test was completed, in order to reduce the amount of film samples that could block the reagent flow. This procedure was much more time-consuming, compared to the simpler gravimetric method. As a result, the Karl Fischer method was not chosen for further applications. 1.2. Equilibrium Sorption Isotherm The equilibrium moisture content (EMC) of the nylon films evaluated in the present study was determined by the gravimetric method. The initial moisture content data obtained by the gravimetric method were then used for EMC calculations (Appendix A). The equilibrium moisture sorption isotherms for the three different nylon films, at 60°C, (Figure 4) displayed upward trends as the relative humidity increased. Selar PA film exhibited higher water sorption levels, than either the Blend or Nylon 6 films. Isotherms of Selar PA (Nylon 6|l6T) and Nylon 6 films at lower temperatures, which were reported by Hernandez (1994), showed a similar trend, with higher moisture sorption for the Selar PA film. Existing moisture sorption data from the literature for Nylon 6 (Ohashi, 1991) and Selar PA (Hernandez, 1989) were plotted along with the experimental data obtained in the present study, to demonstrate the effect of temperature on the moisture sorption behavior of these films. As expected, Nylon 6 (Figure 5) and Selar PA (Figure 6) exhibited descending moisture sorption isotherms as temperature increased. In order to predict moisture dependent properties, such as the permeability of gases and vapors and some thermal behavior of nylon films, an accurate interpolation of the equilibrium moisture content is important. Various mathematical models were selected from the most commonly used moisture sorption equations (Appendix E) and were fitted to the sorption data. Since the experimental data from this study were determined at a limited range of relative humidities, the additional data from the literature 33 Moisture content (weight fraction) 0.07 0.06 1 0.05 - 0.04 J 0.03 J 0.02 - 0.01 - 0.00 0 Nylon 6 I Blend A Selar PA / 20 40 60 80 Relative humidity (%) Figure 4. Moisture sorption isotherms of nylon films at 60°C 34 100 Moisture content (weight fraction) 0.12 0.1 - 0.08 - 0.06 - 0.04 1 0.02 1 o 5 degree Celsius (Ohashi, 1991) A 23 degree Celsius (Ohashi, 1991) I 42 degree Celsius (Ohashi, 1991) c 60 degree Celsius (Experimental Data) I I I I 20 40 60 80 Relative Humidity (%) Figure 5. Moisture sorption isotherms of Nylon 6 at various temperatures 35 100 0.12 0,1 - 9 5 degree Celsius (Hernandez, 1989) A 23 degree Celsius (Hernandez, 1989) I 42 degree Celsius (Hernandez, 1989) A e 0.08 - .9 13 g c 60 degree Celsius (Experimental data) 1:" 2’ 0 5 E 0.06 - d) E 8 2 a .9 § 0.04 l A‘ e 0.02 1 / O / OA/ “ ,V O i l l I 0 20 40 60 80 100 Relative Humidity (%) Figure 6. Moisture sorption isotherms of Selar PA at various temperatures 36 for Nylon 6 (Ohashi, 1991) and Selar PA films (Hernandez, 1989) at other temperatures were also examined to enhance the accuracy of the isotherm modeling. Through a series of calculations, the equation that best described the sorption isotherms of nylon films in this study was found to be the Flory—Huggins equation (Flory, 1953): lnaw=lnV1+(1-V1)+Z(1-V1)2 (21) where aw ,V, and 1 are water activity, volume fraction of water in the polymer and the Flory-Huggins interaction parameter, respectively. The solid lines shown in Figures 4-6 were developed from the Flory-Huggins equation. Since Equation (21) is nonlinear, the Flory-Huggins parameters were determined through an iterative technique. The Newton-Raphson method, combined with the use of spreadsheet tools (Gottfried, 1998) provided a convenient way to determine parameters for the Flory-Huggins equation. In this study, the data were computed using a spreadsheet program (Microsoft® Excel, Microsoft Corporation, WA). Providing an estimate value of 1, the values of V, at each aw were determined by the Newton—Raphson method (Appendix E). Microsoft® Excel Solver program (Frontline System, Inc., NV) was then used for determining the experimental value of I. based on the least squares method (Mehta, 1988). Values of 1 at 5, 23 and 42°C for Nylon 6, calculated from the data taken from Ohashi (1991) and for Selar PA, taken from Hernandez (1989), are shown in Table 2 along with 2’ values from the experimental data at 60°C for Nylon 6, Blend and Selar PA films. For nylon films, 2' values increased with an increase in temperature. This effect indicated smaller interaction between the nylon films and moisture, as the temperature increased (Flory, 1953). 37 Table 2. 2’ values for nylon films at various temperatures. Temperature (°C) Z Nylon 6 Blend Selar PA 5 1.736 1 N/A 1.749 2 23 1.856 ‘ N/A 1.794 2 42 1.950 ‘ NIA 1.886 2 60 2.505 3 2.433 3 2.038 3 ‘ data from Ohashi, 1991. 2 data from Hernandez, 1989. 3 experimental data The sorption isotherm data of Nylon 6 and Selar PA at 5, 23, and 42°C used in this study were reported by the authors (Hernandez, 1989; Ohashi, 1991) to be fitted better with the modified dual mode (Langmuir-Flory-Huggins) sorption model since the sorption data for both films were deviated from Flory-Huggins equation at low relative humidity. The experimental data at 60°C were determined at relatively high humidity (30-80%RH) and were, therefore, insufficient for the estimation of the modified dual mode sorption parameters. As a result, the modified dual mode sorption model was not selected as a choice of models for isotherm fitting. It should also be noted that the data obtained from these literature references were used here in order to demonstrate the effect of temperature and to confirm the accuracy for selecting the best-fit equation. Due to variations in the materials and the test methods, mathematical parameters, such as 2’ values from the Flory-Huggins equation, obtained from both sources may be evaluated together as approximate trends only and should not be used for any critical comparison of material properties. 38 2. Differential Scanning Calorimetry (DSC) Results 2.1. Glass Transition Temperature The glass transition temperatures (T9) of the nylon test films were determined at the midpoint temperature (ASTM E1356-98), using specialized software (Universal Analysis software, TA Instruments Inc., New Castle, DE). There was a decrease in T9 as relative humidity increased (Figure 7). This effect occurs in most polymers (Hatakeyama and Quinn, 1999), particularly hydrophilic ones, where moisture sorbed in the polymer matrix strongly interacts with the polymer chains, disrupting the intermolecular bonds, and consequently plasticizing the polymer. As moisture plasticizes the polymer, the polymer chain segmental mobility increases, resulted in T9 depression. Thermograms of the Blend film, at each respective relative humidity condition, exhibited a single T9, indicating that blends of Selar PA and Nylon 6 are miscible. The T9 values of Blend films at the respective moisture contents are between those of Selar PA and Nylon 6. It can also be seen that the blend of Selar PA and Nylon 6 exhibited a considerably higher Tg values than Nylon 6 itself, despite the low amount of Selar PA (10%) in the blend composition. However, the differences in nylon 6 components (i.e. B36FN for Nylon 6 and B35F for Blend), as well as types and amounts of additives added (BASF, 1995), may contribute to this unexpectedly high Tg value for the Blend film, as compared to Nylon 6. 2.2. Melting Temperature The melting temperatures (T...) of nylon films were determined at the peak of the melt endotherrns. Selar PA yielded no melting temperature, supporting the fact that this film is totally amorphous (Blatz, 1989). As shown in Table 3, Tm values of the Blend film and Nylon 6 were not significantly affected by relative humidity (i.e. moisture content). A possible reason for no variation in Tm values, as the moisture content increased, is that 39 Glass transition temperature (°C) 140 -—c-— Nylon6 ‘ -—I—-Blend 120 - “‘x‘ -—A——SelarPA \A\ 100 - \A\ 80 le \ \\.~‘\“ \‘ ~--!\ 60 - \i 40- \ \\\ \\ u ‘\ 204 \‘\\ “'x- “7. 0 I I I I 0 20 40 60 80 Relative humidity (%) Figure 7. Glass transition temperatures of nylon films as a function of relative humidity 40 100 water initially present in the polymer is removed from the sample through evaporation before the polymer melting process starts. Table 3. Melting temperatures of nylon films pre-equilibrated under various relative humidity conditions Nylon 6 Blend RH (%) EMC (%) Tm (°C) EMC (%) Tm (°C) 0 0.00 221.61 0.00 218.87 29.4 0.88 220.98 0.98 219.01 47.9 1.52 219.03 1.64 220.32 57.7 1.98 220.09 2.15 219.15 80.3 2.92 219.51 3.17 220.67 The expected Tm values of the Blend films, theoretically, should be lower than those of Nylon 6, due to a higher amount of amorphous component. However, statistical analysis (Appendix F) shows no significant difference for Tm values of Blend and Nylon 6, at the confidence level of 95%. As mentioned in the previous section, the differences in nylon 6 components and the addition of additives (nucleating agent and lubricant) may generate difficulty in the comparison of the results from these two polymers. 2.3. Melting Enthalpy and Degree of Crystallinity Since nylon 6 is a semicrystalline polymer with a broad melting range, separating its melting from simultaneous crystallization is difficult, especially when the effects of sorbed moisture are to be evaluated. Traditionally, the film sample can be preheated to the temperature above its T9 and then rapidly quenched in order to eliminate thermal history effects that can cause difficulties in the interpretation of results (TA Instruments, 1998b). However, the preheating process can destroy useful information such as the effects of sorbed moisture to thermal properties of the samples; e.g., moisture can 41 evaporate during the preheating process. Moreover, melting and crystallization neither start nor end at the same temperatures, therefore, different integration limits are required (Hatakeyama and Quinn, 1999). The difficulties in defining the integration limits and some concerns in the determination of nylon crystallinity by conventional DSC techniques have been discussed by Khanna and Kuhn (1997). The authors reported that the level of uncertainty for determining crystallinity of nylon 6 is high due to polymer crystallization between T9 and Tm, which is an exothermic transition at sub-Tm region. The Modulated DSCTM (MDSC) technique was utilized in this study to minimize the aforementioned problems associated with conventional DSC analyses. An example of a MDSC application is illustrated in Figure 8, where the DSC thermogram of Nylon 6 film is shown as reversing, non-reversing, and total heat flow components. When crystallization or melting occurs, the area under an endothermic peak represents the enthalpy of fusion. It can be seen that crystallization of the sample started at approximately 50°C whereas melting started at approximately 150°C. The total enthalpy of fusion calculated from the differences of reversing and non-reversing enthalpy contributions is 62.48 J/g, whereas the enthalpy of fusion determined from the total heat flow is 71.83 J/g. As shown, the present of exothermic relaxation at sub-Tm region in the total heat flow component can incorrectly yield higher heats of fusion, resulting in higher than actual crystallinity. The melting enthalpy and percent crystallinity of Nylon 6 and Blend films determined by MDSC are shown in Table 4. The enthalpy was determined by using specialized software (Universal Analysis software, TA Instruments Inc., New Castle, DE). The percent crystallinity of Nylon 6 was determined from Equation (1) with the heat of fusion value for hypothetical 100% crystalline nylon of 230 J/g (Khanna and Kuhn, 1997). For the Blend, the heat of fusion of 100% crystalline sample value used was 42 66.8 c. “32:30:. 2.2.9.0 m. came. 8.5... .co=8__aam owns. .6 29:96 02.8.03... .m 0.5mm 6.. 93.88569 an em . omm com o? 8.. on o om- . 0 w: . I . _ _ _ . AT . . . N N: .. 934.8 26 .0. 60... 9:892:02 . 0.9.9. .8 o O. _‘n 1 1 O. r: a... 3.8 u 9.8 1 38 n 1.. . A H -mmd % 93%. M... v.0- l OoGONOF .106- m. 26.“. 80.... mc_m._o>om \M) mono W 0.5.me u EA $0.28. u E ( N.O l IV.OI [mod 26: .8: 6.8 9.8. E 0.858 a... 8. E u .2 w.o Nd 43 207 J/g which is 90% of the value used for Nylon 6, as this blend component was composed of 90% Nylon 6. Table 4. Melt enthalpy and percent crystallinity of Nylon 6 and Blend films pre- equilibrated under various relative humidity conditions Melting enthalpy (Jlg) Crystallinity (%) RH (%) Nylon 6 Blend Nylon 6 Blend 0 63.42 54.90 27.57 26.52 29.4 63.40 63.48 27.57 30.67 47.9 60.00 63.46 26.09 30.66 57.7 61.60 54.70 26.78 26.43 80.3 63.00 56.70 27.39 27.39 Statistical analysis (Appendix F) shows no significant difference for the percent crystallinity values of Nylon 6 and Blend at the 95 percent confidence level. The results also show that the increase in relative humidity does not significantly affect the crystallinity of the film samples. This result agrees with the invariability of the melting temperature with moisture content, as mentioned in the previous section. 3. Ethyl Acetate Permeability 3.1. Transmission Rate Profiles Using the Aromatran® 1A, the transmission rate profiles of ethyl acetate vapor through nylon films at 60°C were determined at various relative humidity conditions. The transmission rate profile curves for Nylon 6, Blend, and Selar PA films at various relative humidity conditions are presented in Figures 9-11, respectively. Figures 12-14 show the same plots of the transmission rate profile curves with the transmission rate profile 44 Flux (pg.m'2day'1) 450000 400000 - 350000 300000 - 250000 - I 200000 - 1 50000 1 00000 50000 10 Figure 9. Transmission rate profile curves of ethyl acetate vapor (24.36 mmHg) through Nylon 6 films at various relative humidity conditions and 60°C 20 30 time (hours) 45 40 o 35%RH I 50%RH A 65%RH x 80%RH O 0%RH 50 60 Flux (ug.m'2day'1) 160000 x e 35%RH I 50%RH 140000 — A 65%RH x 80%RH O 0%RH 1 20000 1 00000 80000 60000 40000 I 20000 0 ' I I I 0 10 20 30 40 time (hours) Figure 10. Transmission rate profile curves of ethyl acetate vapor (24.36 mmHg) through Blend films at various relative humidity conditions and 60°C 46 50 70000 0 35%RH I 50%RH A 65%RH 60°00 ‘ x 80%RH O 0%RH 50000 ~ 7" 40000 q > in (P E, 1 U) 3- ’5 a 30000 .4 20000 ~ 10000 0 I j I 0 1 0 20 30 40 50 60 70 80 time (hours) Figure 11. Transmission rate profile curves of ethyl acetate vapor (24.36 mmHg) through Selar PA films at various relative humidity conditions and 60°C 47 450000 o 35%RH I 50%RH A65°/0RH 400000 ‘ x 80%RH 350000 ~ ‘5 1500 « 300000 - <1 ' - 0% RH E. 1000‘ 3 g 500 « 1:" u". 5‘ 250000 . 0- 1., . . ”E 0 20 40 60 2 time (hours) 3 200000 - LL 150000 ~ 100000 - 50000 , A ' ' ' - V 0 I I I I I 0 ‘ 1 2 3 4 time (hours) Figure 12. Transmission rate profile curves of ethyl acetate vapor (24.36 mmHg) through Nylon 6 films at various relative humidity conditions and 60°C 48 Flux (ug.m'2day") 1 60000 140000 - 120000 - 100000 - 80000 ~ 60000 1 40000 — 20000 . X 0 35%RH I 50%RH A 65%RH X 80%RH ‘A A 2000 I; 1500 « SP E. 1000 - . 0%RH U) E: g 500 - LL 0 " r r 0 20 40 60 time (hours) 2 4 6 8 10 time (hours) Figure 13. Transmission rate profile curves of ethyl acetate vapor (24.36 mmHg) through Blend films at various relative humidity conditions and 60°C 49 12 70000 O 35%RH I 50%RH 60000 - A 65%RH X 80%RH 50000 - 2500 '7; 2000 - a: 1500- '7: 40000 ~ 3. 1000 - ' 0%RH CU X J; {- 500 . g 0 ~ . . . g 0 20 40 60 80 E. 30000 - + time (hours) 20000 - + 10000~ I 0 I I T T 0 5 10 15 time (hours) Figure 14. Transmission rate profile curves of ethyl acetate vapor (24.36 mmHg) through Selar PA films at various relative humidity conditions and 60°C 50 curves at dry condition plotted separately, for better comparisons. As seen from the results, the transmission rates of ethyl acetate vapor differ significantly with changes in relative humidity. It is apparent from the respective transmission rate profile curves that the steady state transmission rate increases as relative humidity increases. From the steady state transmission rate, the permeability coefficient (P) can be determined from equation (10). This value alone, despite being an acceptable parameter representing barrier property of materials to moisture or non-interactive gases (Seeley, 1997), cannot provide meaningful information where materials are not in steady state condition, or where the loss of volatile compounds is mainly due to a sorption process. Moreover, the permeability coefficient associated with the diffusion and solubility coefficients can provide more useful and precise interpretation of the mass transfer properties of the materials. These data also contribute to a better prediction of the changes in the quality of packaged products where the gain or loss of organic compounds is a main factor determining their shelf life. Due to these reasons, besides the permeability coefficient, the diffusion coefficient (D) and solubility coefficient (8) were also determined from the permeability data and will be discussed in the following sections. 3.2. Permeability Coefficient (P) The permeability coefficients of nylon films were determined from the steady state transmission rate as defined by equation (10). The experiments were performed at a constant temperature (60°C) and a constant ethyl acetate vapor pressUre (24.36 mmHg). Duplicate samples were tested for each film per each respective relative humidity. Table 5 presents the average permeability coefficients of ethyl acetate vapor through nylon films at various relative humidities. Figure 15 shows the effect of relative humidity on the permeability coefficients. 51 P x 10'17 (kg.m.m'2.sec".Pa") 30 25 ~ -—I——Nylon6 , I ——I—-Blend [I 20 ~ --A- - Selar PA 15 ‘ II (I II I I I ii , ,1 ,’ ,- 5 4 , ’ ,1 A} ,. /’// -"”’:’ I’l/ L’/’r/"”””' ‘__..—- #### ‘l’ 0 ‘:_----—F——l——~— 1 r I 0 20 40 60 80 Relative humidity (%) Figure 15. Effect of relative humidity to permeability coefficients of nylon films at 60°C, ethyl acetate vapor pressure 24.36 mmHg 52 100 Table 5. Permeability coefficients of nylon films at 60°C, and ethyl acetate vapor pressure of 24.36 mmHg. - - - -17 .2 -1 -1 RH (%) Permeability coefficrent x 10 (kg.m.m .5 .Pa ) Nylon 6 Blend Selar PA 0 0.11 10.01 0.12:0.00 0.12 $0.00 35 4.05 i: 0.62 1.55 i 0.25 0.37 i 0.00 50 7.54 i 0.49 3.01 :t 0.47 0.79 i 0.00 65 11.78:0.91 6.63 $0.14 2.21 10.14 80 22.04 :1: 1.53 9.88 i 0.29 3.86 :t 0.03 For all films, an increase in the permeability coefficient was observed with an increase in relative humidity. Nylon 6 film showed higher permeability coefficient values than both the Blend and Selar PA films, whereas the Blend film exhibited permeability coefficient values intermediate between those of Nylon 6 and Selar PA. At dry conditions, the permeability coefficients of all three nylon films are not significantly different. However, as relative humidity increases, permeability coefficient of Nylon 6 film is strongly affected by sorbed moisture, while the permeability coefficient of Selar PA film exhibits smaller changes in comparison. The increases in the permeability coefficients of organic vapor through nylon films, due to sorbed moisture, are not unexpected. As mentioned in the literature review section, Nagaraj (1991) and Lim (1998) also reported the same trends for Selar PA/acetone vapor and nylon 6,6/allyl isothiocyanate vapor systems, respectively. A plasticizing effect of moisture sorbed by the films and the observed permeability constant values can be described. As discussed in section 2.1, the glass 53 transition temperatures (T9) of nylon films decreased as relative humidity increased (Figure 7). Over the whole range of relative humidity conditions selected in this study, the T9 values of Nylon 6 film are well below the test temperature (60°C). The relatively high permeability coefficient values obtained for Nylon 6 film at humidified condition can be explained by the ease of ethyl acetate permeation through Nylon 6 film above its T9, due to enhanced polymer chain segmental mobility caused by sorbed moisture. Based on this argument, the observed smaller effect of sorbed moisture for Selar PA film is due to the fact that Tg values of Selar PA, at all test conditions, are above the test temperature, resulting in limited polymer chain segmental mobility. The effect of sorbed moisture on the permeability coefficient of the Blend film illustrates a case where its Tg values range from above the test temperature at low relative humidity conditions to values below the test temperature at high relative humidity conditions. At 0% and 35%RH, T9 values of the Blend are well above the test temperature, in contrast, its Tg values are below the test temperature at 65% and 80%RH. As shown in Figure 7, the T9 of the Blend film reaches 60°C, i.e. test temperature, at approximately 60%RH. Figure 11 showed a sharp increase in the permeability coefficient above 60%RH. which supports the proposal that the permeability coefficient values increase markedly as moisture plasticizes the film sample, to the extent where its T9 is below the test temperature. Although the corresponding Tg depression and permeability coefficient increase is well described by the plasticizing effect of moisture for the Blend film, the increases in the permeability coefficients at high humidities for Selar PA and Nylon 6 are not as well understood. As shown in Figure 15, significant increases in permeability coefficients for Selar PA and Nylon 6 were observed at high humidity conditions, despite small changes in T9 values (Figure 7). This may be explained as follows. T9 values determined in this present study were the midpoint temperatures (as defined by ASTM E1356—98). A major 54 change in polymer chain mobility, which leads to a significant change in the permeability coefficient, can occur initially at the onset of the T9 ranges. Thus, at the test temperature, the onset Tg may be reached (Khanna et al., 1995) in spite of the reported Tg above the test temperature. In addition, the sorption of ethyl acetate vapor during the permeability experiment may cause further Tg depression (Lim et al., 1998). Moreover, variations in test conditions (e.g. relative humidity and temperature) generated by the Aromatran® 1A, as well as errors associated with the reported results can be taken into account for the deviation of the unexpected high permeability coefficients. 3.3. Estimation of Diffusion Coefficient (D) and Consistency Test From the first order solution to Fick's Law as described in Equation (16) and (17), the diffusion coefficients of nylon films at various relative humidities were estimated from Equation (18). The values of X at any time, t, over the transient portion of the transmission rate profile were determined by the Newton-Raphson method (Appendix H). The values of estimated diffusion coefficients (Davg) for nylon films determined from the aforementioned equation are presented in Table 6-8. 0.... values in Table 6-8 are diffusion coefficients determined from Equation (14), which is the equation used for diffusion coefficient determination by the Aromatran®1A's software. To demonstrate the effect of relative humidity on the diffusion coefficient, the average D values (Dam) of nylon films were plotted as a function of relative humidity in Figure 16. The Davg value was chosen to represent the estimated diffusion coefficient because it was determined from a range of unsteady state transmission rate values instead of only one point, as was the Dc... value. The diffusion coefficients are affected by moisture in the same trend as the permeability coefficient values and should be described well by the plasticizing effect of moisture on the nylon films, as discussed in the previous section. However, at 80%RH, Nylon 6 shows a distinctively high diffusion coefficient. The accuracy and validity of the 55 $86 mvmd 8N6 N3 3% SN 2196.... mFmFN... N 286 FNod F85 mNm NNm «N... 293. 2.53 F om $86 9.3 8nd 8.: 8: 26 2.53 293 N 886 BB New... 8.: NSF 86F mF-m8.F NFmFmF F 8 98.0 26.0 913 SN NSF ooNF mFmomF mmeNF N R85 N86 ONE. 98 8.: VNNF NmemF NmeNF F om 886 F86 F93 86.. SN 98 vaNnm 3.53 N F866 33 R3 85 RN 8.: 308.5 Ewes... F mm F86... F85 m3... 886 8va BEN 2-9.3 mFmvem N 58.0 89o N33 ONE 088 SEN 3mm? mFmNE F o a. NV. .0. a. e... a. no. .6. 9.3 ENE. .80 ENE. ed .8 mass... 5. .5325 .69? 2.203 $50 9.5:. oméu .o meF 5:03.38 Lo.— mLoFoEEma vcm 35.0508 5.0.2.6 umFmESmm .0 03m... 0000 Ucm wCOE—ucoo 3:353: GEN—Em; m30tfl> um EE 0 CO_>Z 56 N080 N80 240 NFwN N20 80F 2-0va 2.005 N 0000.0 0N0... 09.0 NSF Neo QNN mF-mmm.N mFmEN F 00 88.0 «2.0 N90 3% 8.0 NSF NFmNNF .NFmNNF N 88.0 08.0 09.0 008 8.0 $2 NmeFF mFmFNF F 00 F080 N80 «NE. 86 «FF NBN vaNNN 3.32 N E80 N80 N30 88 N3 88 3-08.0 3-08.... F om 88.0 08.0 4N3 82F N.N 88 3.93 3.020 N 030.0 :60 84.0 008 F 080 3.08... 3-08.0 F mm 030.0 N000 ONE 830 N0 80FN 8.08... 3.00; N 88.0 80.0 08.0 88... F0 80FN 8.000... 2.03... F o 9. N0. 1 a. e... a. .3. a. 9.8. ENE. .80 .005. 9.0 .o: 2056... :m 0600 0:0 0:020:00 3.0.82. 02.0.0. 000.09 .0 EE 0005 0000.5 .000> 99000 $50 9.0:: oméw .0 F09 5:20.008 .0. 3208900 000 300.0508 00.03.50 020:..me .N. 0.00... 57 88.0 0000 F30 080 SN .0: 3.80.0 3.00.8 N 88.0 80.0 08.0 .000 .08 8FN 3.0000 3.000. F 8 88.0 0000 0.3.0 080 0:0 NRN 3.080 3.030 N 88.0 000.0 :40 N80 0va 008 3-08.0 1-08.0 F 00 88.0 80.0 04.0 0N8F v0.9 0:: 30:8 vF-mFmN N .080 08.0 8.0 0NF0F N08 8.0 3-08N vF-m00N F 00 88.0 80.0 000.0 088 088 00F FF 3-000F 3-003 N 88.0 80 .080 088 088 0N0FF $-08F $-08F F 00 880 N00 03.0 880 088 808 0708.0 0708.0 N 0800 F000 08.0 0080 808 0NRN 0708.0 0F-mNN0 F 0 N. .0. .0. .0. .8... .0. 3. .0. 88. .00.... .80 .002. 9.0 .0: 200.00 :0 0030.5 .000> 0.0.000 350 mIEE omém .0 F00. 8020.008 .0. 0.200.800 000 000.0508 00.03:.0 00.0.0.00m .0 0.00..- oooo 000 0000.008 3.0.0.3... 02.0.0. 030.00> F0 EE <0. .0_0m 58 Davg x 10'14 (m2.s"1) 45 40 0 II I I 35 — [I , s— -—o—- Nylon6 - I ——l-— Blend ,’ I ——A-— Selar PA - I 30 « , I I I I -’ l I 25 ~ ,’ I I I ' I I I ’ I ’ I 20 ~ ¥ ,’ l I, I // ’l h I // ’ / I / I 15 — ,I ,1 ’ / I" ’1 , i I, // z, / 10 .4 ’1 ll // I / ,é ,/ A / / l/ // /// / / / / z/ / 5 _- // I,’ ’1 I ’é’ I / ’I I // i” ,l // ,”’ I x I’,’ ”_,"‘ g/xx’ ___________ r" 0 I I l I I O 20 40 60 80 Relative humidity (%) Figure 16. Effect of relative humidity to diffusion coefficients of nylon films at 60°C, ethyl acetate vapor pressure 24.36 mmHg 59 100 diffusion coefficient estimation in this study were verified by performing a numerical consistency test of the permeability data as described by Gavara and Hernandez (1993). The parameters for consistency evaluation for permeability data of ethyl acetate through nylon films are also presented in Table 6—8. The values of K1 and K2 calculated from the experimental data ranged within 10% of the theoretical values given in Equations (19) and (20) for Blend and Selar PA films. For Nylon 6 films, however, these values deviated from the theoretical values by as much as 24% at high relative humidity conditions. These high deviations may be due to improper sampling rate because, in the present study, the test parameters, except for relative humidity, were set equally for all tests in order to minimize the variation of the experiments. Nylon 6, especially as exposed to high relative humidity conditions, exhibited extremely high and rapid transmission rates. The transmission rate values at the unsteady state portion determined in this study may be inadequate for an accurate estimation of the diffusion coefficient at high relative humidity. Thus, this might result in the inaccurate diffusion coefficient values determined at high humidities, as stated previously. 3.4. Solubility Coefficient (8) As both permeability and diffusion coefficients are known, the solubility coefficient (8) may be calculated from the relationship of P, D and S as expressed in Equafions(22) S = MD (22) Assuming that the diffusion coefficient values determined in this study were accurate, the solubility coefficient values for the respective nylon films were calculated and are summarized in Table 9. The plot of solubility coefficients as a function of relative humidity is also shown in Figure 17. 60 Table 9. Solubility coefficients of nylon films at 60°C, and ethyl acetate vapor pressure of 24.36 mmHg. Solubility coefficient x 10‘4 (fim‘an‘) RH (%) Nylon 6 Blend Selar PA 0 1.71 i 0.02 1.34 i 0.03 1.94 :t 0.05 35 4.63 i016 3.55 10.14 2.33 00.10 50 6.01 :t 0.37 4.92 i 0.56 3.19 t 0.34 65 6.09 i 1.10 5.45 i 0.10 3.58 :l: 0.40 80 5.86 10.45 4.81 i 1.74 4.41 00.59 Nylon 6 film exhibited higher solubility coefficient levels than the Blend and Selar PA films, while the solubility coefficient values of the Blend films were intermediate between those of Nylon 6 and Selar PA films. The solubility coefficients of Nylon 6 and Blend films follow ascending trends at relative humidity up to 65 percent, then descended at higher humidity. The solubility coefficient of Selar PA film displayed an upward trend as the relative humidity increased. The non-uniform patterns of the solubility coefficients of these nylon films at high relative humidity may be due to the high errors associated with the estimation of diffusion coefficients at high relative humidity, as mentioned in the previous section. Concerning the high level of errors at high relative humidity condition, the solubility coefficient, in general, increases as relative humidity increases. 61 7 . --O--Nylon6 --I--Blend 6— --*--SelarPA } """"" “Ni 5— . i: u “A s x 10‘ (kg.m‘3.Pa'1) .b 2 1:1." Q. P" 1 0 o , T - - 0 20 40 60 80 100 Relative humidity (%) Figure 17. Effect of relative humidity to solubility coefficients of nylon films at 60°C, ethyl acetate vapor pressure 24.36 mmHg. (This image is originally presented in color). 62 CONCLUSIONS The effect of relative humidity on the transport properties of ethyl acetate vapor through a series of nylon films was studied by an isostatic permeability test procedure. The nylon films used in this study were a semicrystalline nylon 6 film, an amorphous nylon (nylon 6|l6T) film, and a film made from blends of nylon 6 and nylon 6|l6T. For better understanding of the moisture dependent characteristics of these films, the equilibrium moisture sorption isotherms of nylon films were constructed. The thermal analysis technique was also utilized to evaluate the effect of sorbed moisture on the film properties. The equilibrium moisture sorption isotherm of all films exhibited upward trends as relative humidity increased. The comparisons of sorption isotherm at 5, 23, 42, and 60°C showed that the moisture sorption for all films decreased as temperature increased. Various equations were fitted to the sorption isotherms and the Flory- Huggins equation was found to best describe the sorption isotherm of nylon films in this study. From the differential scanning calorimetry (DSC) analysis, there was no effect of sorbed moisture on the melting temperatures and degree of crystallinity of the nylon films. However, there were significant changes in the glass transition temperatures of these films, as a function of sorbed moisture. For all films, the glass transition temperature decreased as relative humidity increased. The permeability (P), diffusion (D), and solubility (S) coefficients of ethyl acetate vapor through the nylon films were determined at various relative humidity conditions. The results showed an ascending trend for P, D, and S as relative humidity increased. The increases in these coefficient values can be explained by the plasticizing effect of 63 moisture sorbed in the films as shown by a decrease in the glass transition temperature. The results from the consistency test for the permeability data suggested that the experimental parameters were well controlled at low relative humidity levels but deviated from the theoretical values at high relative humidity. 64 FURTHER STUDIES The results obtained from this study showed the effect of sorbed moisture on the permeability of ethyl acetate vapor through nylon films. These results, however, were obtained from a very limited range of test parameters and conditions. In order to develop a better understanding of the factors affecting the permeability of organic vapors through nylon films, a number of additional studies can be proposed. Additional organic permeants with different functionalities should be evaluated in a series of permeability experiments. The experiments can be performed at a constant vapor concentration and constant temperature, and at various relative humidity conditions. The objective of these studies is to determine the effect of penetrant polarity and molecular structure on the permeability of nylon films, as a function of relative humidity. Moreover, the film made from blends of nylon 6 and amorphous nylon can be evaluated for the cOmponent composition that yields optimum barrier. This study will contribute to further developments in commercial uses of the blends from nylon 6 and amorphous nylon. 65 APPENDICES 66 APPENDIX A MOISTURE CONTENT CALCULATIONS Initial moisture content calculation The initial moisture content (lMC) of film samples was determined by the gravimetric method, and IMO was calculated on dry basis from; W--WI) %IMC = ( x100 (23) I where W, = initial weight of film sample W,= final weight of film sample after drying Equilibrium moisture content calculation The equilibrium moisture content (EMC) of film samples was calculated from; %EMC = [w — 1] x 100 (24) where M, = final weight of film sample M,- = initial weight of film sample IMC = initial moisture content of film sample 67 APPENDIX B RELATIVE HUMIDITY OVER SATURATED SALT SOLUTIONS Table 10. Relative humidity of air over saturated aqueous salt solutions at 60°C Temperature (°C) Saturated Solution Expected Measured Magnesium chloride MgCI2 . 6H20 29.31 29.4 Potassium nitrite KNo2 47.92 47.9 Sodium nitrite NaNo3 57.72 57.7 Sodium chloride NaCl 74.51 74.3 Ammonium sulfate (NH4)2SO4 77.51 80.3 ‘ Greenspan, L. 1977. "Humidity Fixed Points of Binary Saturated Aqueous Solutions," Journal of Research of the National Bureau of Standards-A. Physics and Chemistry, 81A(1):89-96. 2 Modern Control, 1996. Aramotran 1A Operator's Manual, Modern Control, Inc., Minneapolis, MN. 68 APPENDIX C MOISTURE CONTENT DATA Initial Moisture Content Data Table 11. Initial moisture content of nylon films determined by Karl Fisher method Sample no. Nylon 6 Blend Seler PA 1 2.72 2.83 2.24 2 2.69 3.08 2.01 3 2.80 2.74 2.46 Avg. 2.74 2.88 2.24 Std. Dev. 0.06 0.18 0.23 Table 12. Initial moisture content data of Nylon 6 film determined by gravimetric method Sample no. Initial wt. (9) Dry wt. (9) % IMC 1 0.1136 0.1106 2.71 2 0.1081 0.1052 2.76 3 0.1025 0.0999 2.60 Avg. 2.69 Std. Dev. 0.08 69 Table 13. Initial moisture content data of Blend film determined by gravimetric method Sample no. Initial wt. (9) Dry wt. (9) % IMC 1 0.1362 0.1323 2.95 2 0.1271 0.1234 3.00 3 0.1293 0.1255 3.03 Avg. 2.99 Std. Dev. 0.04 Table 14. Initial moisture content data of Selar PA film determined by gravimetric method Sample no. Initial wt. (9) Dry wt. (9) % IMC 1 0.15 0.15 2.52 2 0.15 0.15 2.51 3 0.15 0.15 2.47 I Avg. 2.50 Std. Dev. 0.03 . 70 Statistical Analysis of Initial Moisture Contents Determined from Karl Fischer and Gravimetric Methods Table 15. t-test for initial moisture content of Nylon 6 film determined by Karl Fisher and gravimetric methods, at the 95 percent confidence level Karl Fisher Gravimetric Mean 2.73667 2.69058 Variance 0.00323 0.00629 Observations 3 3 Hypothesized Mean Difference 0 df 4 t Stat 0.81790 P(T<=t) one-tail 0.22967 t Cn'tical one-tail 2.13185 P(T<=t) two-tail 0.45934 t Critical two-tail 2.77645 Table 16. t-test for initial moisture content of Blend film determined by Kari Fisher and gravimetric methods, at the 95 percent confidence level Karl Fisher Gravimetric Mean 2.88333 2.99137 Variance 0.03103 0.00164 Observations 3 3 Pooled Variance 0.01634 Hypothesized Mean Difference 0 df 4 t Stat -1.03526 P(T<=t) one-tail 0.17951 t Critical one-tail 2.13185 P(T<=t) two-tail 0.35903 t Critical two-tail 2.77645 71 Table 17. t-test for initial moisture content of Selar PA film determined by Karl Fisher and gravimetric methods, at the 95 percent confidence level Karl Fisher Gravimetric Mean 2.23667 2.50073 Variance 0.05063 0.00064 Observations 3 3 Hypothesized Mean Difference 0 df 2 t Stat -2.01992 P(T<=t) one-tail 0.09041 t Critical one-tail 2.91999 P(T<=t) two-tail 0.18082 t Critical two-tail 4.30266 72 APPENDIX D EQUILIBRIUM MOISTURE CONTENT DATA Table 18. Equilibrium moisture content data of Nylon 6 film determined at 60°C RH Sample no. initial wt. (9) final wt. (9) EMC (%) avg EMC Std. Dev. N-1 0.0829 0.0814 0.83 29.4 N-2 0.0921 0.0905 0.91 0.88 0.04 N-3 0.0922 0.0906 0.91 N-1 0.0854 0.0846 1.73 47.9 N-2 0.0924 0.0913 1.47 1.52 0.13 N-3 0.0832 0.0823 1 .58 N-1 0.0918 0.0911 1.91 57.7 N-2 0.0907 0.0901 2.01 1.98 0.07 N-3 0.0933 0.0927 2.03 N-1 0.0882 0.0881 2.57 74.3 N-2 0.0872 0.0871 2.57 2.58 0.00 N-3 0.0940 0.0939 2.58 N-1 0.0887 0.0890 3.04 80.3 N-2 0.0932 0.0935 3.02 2.92 0.20 N-3 0.0950 0.0950 2.69 73 Table 19. Equilibrium moisture content data of Blend film determined at 60°C RH Sample no. initial wt. (9) final wt. (9) EMC (%) avg EMC Std. Dev. B-1 0.0925 0.0907 0.99 29.4 B-2 0.0967 0.0948 0.97 0.98 0.06 33 0.0977 0.0957 0.88 B-1 0.0938 0.0926 1.67 47.9 B-2 0.0895 0.0883 1.61 1.64 0.03 B-3 0.0987 0.0974 1 .63 B-1 0.1007 0.0997 1.97 57.7 B-2 0.0961 0.0954 2.24 2.15 0.16 B-3 0.1242 0.1233 2.25 B-1 0.0987 0.0985 2.78 74.3 B-2 0.0926 0.0924 2.77 2.78 0.01 B-3 0.1002 0.1000 2.79 B-1 0.1024 0.1025 3.09 80.3 B-2 0.1143 0.1146 3.26 3.17 0.09 B-3 0.1180 0.1182 3.17 74 Table 20. Equilibrium moisture content data of Selar PA film determined at 60°C RH Sample no. initial wt. (9) final wt. (9) EMC (%) avg EMC Std. Dev. S-1 0.1042 0.1032 1.52 29.4 S-2 0.1069 0.1059 1.54 1.60 0.12 S-3 0.1071 0.1063 1.73 S-1 0.1068 0.1071 2.79 47.9 S-2 0.1094 0.1094 2.50 2.72 0.19 S-3 0.1130 0.1134 2.86 S-1 0.1165 0.1174 3.29 57.7 S-2 0.1209 0.1218 3.26 3.34 0.11 S-3 0.1052 0.1062 3.47 S-1 0.1082 0.1102 4.39 74.3 S—2 0.1129 0.1151 4.50 4.43 0.06 S-3 0.1084 0.1104 4.39 S-1 0.1180 0.1206 4.76 80.3 S-2 0.1139 0.1165 4.84 4.80 0.04 8-3 0.1064 0.1088 4.81 75 APPENDIX E SORPTION ISOTHERM MODELING Mathematical Models Used for Isotherm Modeling Chen Equation M=k—In(;lnAw) where M is equilibrium moisture content, AW is water activity, k and a are constants (Kirloskar, 1991). Linearized form; In(—In Aw) = k —aM Henderson Equation M = exp{%[ln(-In(1— Aw)) — In K]} where M is equilibrium moisture content, AW is water activity, n and K are constants (Kirloskar, 1991 ). Linearized form; In[—In(1-Aw)]= nInM+an Guggenheim-Anderson-de Boer (GAB) Equation w cm, W.- =(1—kAWII1—M- +CkA-I where Aw is water activity, W is water content on dry basis, Wm is water content corresponding to saturation of all primary adsorption sites by one water molecule, C is the Guggenheim constant, and k is a factor correcting properties of the multilayer molecules with respect to the bulk liquid (Schar and Ruegg, 1985). 76 Quadratic form; i_ 2 W-aA~+flA-v+7 where “l‘ l a=—— ——1 w,,, c 1 2 =_1__ fl Wm[ C] _ 1 7’mek Flory-Huggins Equation In a,,=In v, +(1 - v,)+1(1— v,)’- where aw ,V, and Z are water activity, volume fraction of water in the polymer and the Flory-Huggins interaction parameter, respectively (Flory, 1953). 77 Visual Basic Program for Newton-Raphson Method Used for Determining Flory-Huggins Interaction Parameter (x) Function NewRaph(x, b, n, a) ' For each aw value ' x = aw/10 . b = X ' n = number of iterations ' a = aw NewRaph = x For k = 1 To n ' F = Flory-Huggins Equation ' D = First derivative of Flory-Huggins Equation F=x*Exp((1-x)+b*(1-x)*(1-x))-a D=(EXP((1-X)+b*(1-X)*(1-X)))*(1-X*(2*b*(1-X)+1)) x=x-F/D Next k NewRaph = x End Function 78 APPENDIX F DSC ANALYSIS Table 21. DSC Data of Nylon 6 Films AH: (Jlg) RH (%) T9 (C°) Tm (C°) . _ crystallinity (%) reversnng non-reversung total 0.00 52.49 221.61 149.90 86.48 63.42 27.57 29.4 28.06 220.98 198.70 135.30 63.40 27.57 47.9 15.34 219.03 202.60 142.60 60.00 26.09 57.7 11.77 220.09 190.50 128.90 61.60 26.78 80.3 6.03 219.51 198.70 135.70 63.00 27.39 Table 22. DSC Data of Blend Films AH, (Jlg) RH (%) T9 (C°) Tm (C°) . . crystallinity (%) reversung non-reversrng total 0.00 80.33 218.87 210.00 155.10 54.90 26.52 29.4 70.13 219.01 152.30 88.82 63.48 30.67 47.9 66.64 220.32 137.90 74.44 63.46 30.66 57.7 59.03 219.15 203.70 149.00 54.70 26.43 80.3 31.23 ‘ 220.67 242.60 185.90 56.70 27.39 Table 23. DSC Data of Selar PA Films AH: (Jlg) RH (%) Tg (C°) Tm (C°) _ . crystallinity (%) reversrng non-reversnng total 0.00 127.34 n/a n/a n/a nla n/a 29.4 1 19.05 n/a n/a nla n/a n/a 47.9 104.10 n/a n/a n/a n/a n/a 57.7 93.41 n/a n/a n/a n/a nla 80.3 68.16 n/a n/a n/a nla nla 79 Table 24. t-test for melting points of Nylon 6 and Blend films determined by DSC analysis at the 95 percent confidence level Nylon 6 Blend Mean 220.24 219.60 Variance 1 .1 1098 0.68668 Observations 5 5 Pooled Variance 0.89883 Hypothesized Mean Difference 0 df 8 t Stat 1.06736 P(T<=t) one-tail 0.15848 t Critical one-tail 1.85955 P(T<=t) two-tail 0.31696 t Critical two-tail 2.30601 Table 25. t-test for percent crystallinity of Nylon 6 and Blend films determined by DSC analysis at the 95 percent confidence level Nylon 6 Blend Mean 27.08 28.33 Variance 0.41272 4.66361 Observations 5 5 Pooled Variance 2.53817 Hypothesized Mean Difference 0 df 8 t Stat -1.24292 P(T<=t) one-tail 0.12455 t Critical one-tail 1.85955 P(T<=t) two-tail 0.24909 t Critical two-tail 2.30601 80 APPENDIX G PERMEABILITY DATA Table 26. Data for permeability of 24.36 mmHg ethyl acetate vapor through Nylon 6 film, at various relative humidity conditions and 60°C RH Sample No. TR P D S iltg.m'2.day'1 kg.m.m'2.s'1.Pa'1 kg.m'3.Pa'1 m2.s'1 o 1 1935.61 1.14E-18 6.72E-15 1.771500 2 1717.11 1.01 E-18 5.84E-15 1.73E-02 35 1 76418.2 4.49E-17 9.46E-14 4.63E+00 2 61471.3 3.61 E-17 7.99E-14 1.14E-01 50 1 122554 7205-17 1255-13 6.01E-I-00 2 134219 7.88E-17 1.26E-13 2.62E—01 65 1 211427 1.24E-16 1.81E-13 6.09E+00 2 184622 1.08E-16 2.04E-13 7.77E-01 80 1 356764 2.10E-16 3.39E-13 5.86E+00 2 397275 2.33E-16 4.21E-13 3.16E-01 Table 27. Data for permeability of 24.36 mmHg ethyl acetate vapor through Blend film, at various relative humidity conditions and 60°C RH Sample No. TR P D S i.tg.m'2.day'1 kg.m.m'2.s'1.Pa'1 kg.m'3. Pa'1 m2.s'1 0 1 1856.66 1.20E-18 9.04E-15 1.32E-04 2 1846.69 1.19E-18 8.73E-15 1.36E-04 35 1 26826.4 1.73E-17 5.01 E14 3.45E-04 2 21387.6 1.38E-17 3.79E-14 .3.64E-04 50 1 41512 2.68E-17 5.03E-14 5.32E-04 2 51762 3.34E-17 7.37E-14 4.53E-04 65 1 101327 6.53E-17 1.21 E-13 5.38E-04 2 104411 6.73E-17 1.22E—13 5.52E-04 80 1 150089 9.67E-17 2.70E-13 3.58E-04 2 168216 1.08E-16 1 .79E-13 6.04E-04 81 Table 28. Data for permeability of 24.36 mmHg ethyl acetate vapor through Selar PA film, at various relative humidity conditions and 60°C RH Sample No. TR P D S ttg.m'2.day'1 kg.m.m'2.s'1.Pa'1 kg.m‘3.Pa'1 m2.s'1 0 1 1973.55 1.19E-18 6.27E-15 1.91E-04 2 1925.74 1.17E-18 5.89E-15 1.98E-04 35 1 6075.5 3.68E-18 1.53E—14 2.40E—04 2 5971.8 3.61 E-18 1.60E-14 2.26E-04 50 1 13063 7.91 E-18 2.68E-14 2.95E-04 2 13100 7.93E-18 2.31E-14 3.43E-04 65 1 38166 2.31 E-17 5.98E-14 3.86E-04 2 34968 2.12E-17 6.41 E-14 3305-04 80 1 63422 3.84E-17 7.96E-14 4.83E-04 2 64186 3.88E-17 9.75E-14 3.99E-04 82 APPENDIX H ESTIMATION OF DIFFUSION COEFFICIENT Visual Basic Program for Newton-Raphson Method Used for Estimation of Diffusion Coefficient Values Function NewRQ(x, a, n) ' At any time, t ' x = estimated value of X ' a = Ft/Fss ' n = number of iterations NewRQ = x For k = 1 To n F = 4 I Sqr(Application.Pi()) * Sqr(x) * Exp(-x) - a D = 4 / Sqr(Application.Pi()) * (Exp(-x) * (0.5 / Sqr(x)) - (Sqr(x) * Exp(-x)) x=x-F/D Next k NewRQ = x End Function 83 Sample : Nylon 6 1.65 mil Test temperature 60°C Data for Diffusion Coefficient Estimation Relative humidity 0% Sample no. 1 t (hours) F. (99.m'2.day") FJFs. x 1/X 5.09 234.211 0.1210 3.5609 0.2808 5.59 288.993 0.1493 3.3149 0.3017 6.09 389.382 0.2012 2.9602 0.3378 6.59 459.513 0.2374 2.7595 0.3624 7.09 561.842 0.2903 2.5113 0.3982 7.59 597.040 0.3084 2.4351 0.4107 8.09 713.661 0.3687 2.2077 0.4530 8.59 758.651 0.3919 2.1282 0.4699 9.09 852.864 0.4406 1.9734 0.5067 9.59 903.764 0.4669 1.8952 0.5276 10.09 962.344 0.4972 1.8092 0.5527 10.59 1030.44 0.5324 1.7137 0.5835 11.09 1091.57 0.5639 1.6315 0.6129 11.59 1147.06 0.5926 1.5593 0.6413 12.09 1185.34 0.6124 1.5106 0.6620 12.59 1253.80 0.6478 1.4254 0.7016 13.09 1286.79 0.6648 1.3851 0.7220 13.59 1321.02 0.6825 1.3437 0.7442 14.09 1377.12 0.7115 1.2764 0.7834 14.59 1395.91 0.7212 1.2540 0.7974 Fss = 1935.61 slope (hr'1) = 0.06 D (m2.s“) = 6.72E-15 r2 = 0.9991 84 Sample : Nylon 6 1.65 mil Test temperature 60°C Relative humidity 0% Sample no. 2 t (hours) Fr (99.029871) Fr/Fss x W 5.87 189.49 0.1104 3.6678 0.2726 6.20 248.15 0.1445 3.3533 0.2982 6.53 279.82 0.1630 3.2116 0.3114 6.87 307.73 0.1792 3.0934 0.3228 7.20 368.03 0.2143 2.8837 0.3468 7.53 399.62 0.2327 2.7837 0.3592 7.87 433.67 0.2526 2.6836 0.3726 8.20 492.89 0.2870 2.5252 0.3960 8.53 517.21 0.3012 2.4650 0.4057 8.87 572.87 0.3336 2.3359 0.4281 9.20 615.12 0.3582 2.2448 0.4455 9.53 642.74 0.3743 2.1881 0.4570 9.87 667.44 0.3887 2.1391 0.4675 10.20 720.45 0.4196 2.0386 0.4905 10.53 742.86 0.4326 1.9979 0.5005 10.87 783.88 0.4565 1.9257 0.5193 11.20 801.96 0.4670 1.8948 0.5278 11.53 830.28 0.4835 1.8475 0.5413 11.87 872.62 0.5082 1.7788 0.5622 12.20 890.89 0.5188 1.7499 0.5715 12.53 923.88 0.5380 1.6987 0.5887 12.87 965.96 0.5625 1.6350 0.6116 13.20 1009.09 0.5877 1.5716 0.6363 13.53 1023.21 0.5959 1.5511 0.6447 13.87 1054.88 0.6143 1.5058 0.6641 14.20 1078.34 0.6280 1.4727 0.6790 14.53 1116.19 0.6500 1.4200 0.7042 14.87 1127.74 0.6568 1.4041 0.7122 15.20 1149.09 0.6692 1.3748 0.7274 15.53 1162.76 0.6772 1.3561 0.7374 15.87 1196.90 0.6970 1.3098 0.7635 16.20 1219.40 0.7101 1.2795 0.7816 16.53 1215.52 0.7079 1.2847 0.7784 16.87 1249.92 0.7279 1.2385 0.8074 17.20 1279.74 0.7453 1.1985 0.8344 17.53 1279.56 0.7452 1.1988 0.8342 17.87 1301.53 0.7580 1.1693 0.8552 85 F. (pg.m'2.day'1) t (hours) Fr/Fss x 1Ix 18.20 1310.70 0.7633 1.1570 0.8643 18.53 1338.75 0.7797 1.1193 0.8934 18.87 1342.19 0.7817 1.1147 0.8971 19.20 1353.40 0.7882 1 .0996 0.9095 F. = 1717.11 slope (hr'1) = 0.05 D (m2.s") = 5.84E-15 12 = 0.9991 86 Sample : Nylon 6 1.65 mil Test temperature 60°C Relative humidity 35% Sample no. 1 t (hours) Ft (us-m'z-day") FtlFss x 1/X 0.14 0.00000 0.0000 33.2855 0.0300 0.30 1789.90 0.0234 5.4123 0.1848 0.47 16664.5 0.2181 2.8628 0.3493 0.64 33269.8 0.4354 1.9894 0.5027 0.80 46540.2 0.6090 1.5188 0.6584 0.97 55409.4 0.7251 1.2450 0.8032 1.14 60963.2 0.7978 1.0773 0.9283 1.30 65107.9 0.8520 0.9478 1.0551 1.47 68331.9 0.8942 0.8395 1.1912 1.64 70356.5 0.9207 0.7645 1.3080 1.80 71534.7 0.9361 0.7165 1.3956 1.97 73208.4 0.9580 0.6387 1.5657 2.14 73612.0 0.9633 0.6172 1.6201 2.30 73912.2 0.9672 0.6002 1.6660 F. = 76418.2 slope (hr") = 0.78 D (m2.s") = 9.46E-14 r2 = 0.9901 87 Sample : Nylon 6 1.65 mil Test temperature 60°C Relative humidity 35% Sample no. 2 t (hours) Ft (Hg-m'zdaY‘) Ft/Fss x 1/X 0.07 0.00000 0.0000 33.2855 0.0300 0.24 392.400 0.0064 6.8285 0.1464 0.40 5562.80 0.0905 3.8964 0.2566 0.57 16453.4 0.2677 2.6120 0.3828 0.74 27265.3 0.4435 1.9645 0.5090 0.90 34495.0 0.5612 1.6386 0.6103 1.07 40941.0 0.6660 1.3822 0.7235 1.24 44987.0 0.7318 1.2295 0.8134 1.40 48473.7 0.7886 1.0987 0.9102 1.74 53531.9 0.8708 0.9006 1.1103 1 .90 55356.5 0.9005 0.8222 1.2162 2.07 56579.3 0.9204 0.7653 1 .3067 2.24 58710.1 0.9551 0.6500 1.5385 Fss = 61471.3 slope (hr") = 0.66 D (m2.s") = 7.99E-14 12 = 0.9956 88 Sample : Nylon 6 1.65 mil Test temperature 60°C Relative humidity 50% Sample no. 1 t (hours) Fr (ug.m'2.day") Ft/Fss x W 0.31 16038.0 0.1195 3.5755 0.2797 0.52 69126.4 0.5150 1.7602 0.5681 0.64 84880.4 0.6324 1 .4621 0.6839 0.81 99692.9 0.7428 1.2043 0.8303 0.97 109951 0.8192 1.0269 0.9738 Fss = 134219 slope (hr’1) = 1.03 D (m2.s") = 1.25E-13 r2 = 0.9873 Sample : Nylon 6 1.65 mil Test temperature 60°C Relative humidity 50% Sample no. 2 t (hours) Ft (HQ-m'z-daYJ) Ft/Fss X 1IX 0.24 5767.6 0.0471 4.6373 0.2156 0.40 39921 .6 0.3257 2.3662 0.4226 0.57 68644.6 0.5601 1.6413 0.6093 0.74 86983.5 0.7098 1.2804 0.7810 0.90 98461.5 0.8034 1.0641 0.9398 1.07 1052065 0.8585 0.9318 1.0732 Fss = 1225540 slope (hr") = 1.03 D (m2.s“) = 1.26E-13 r2 = 0.9947 89 Sample : Nylon 6 1.65 mil Test temperature 60°C Relative humidity 65% Sample no. 1 t (hours) Fr (us-m'z-day") Ft/Fss x W 0.24 30799.10 0.1457 3.3439 0.2991 0.41 123274.30 0.5831 1.5831 0.6317 0.57 166774.30 0.7888 1.0981 0.9106 0.93 196033.30 0.9272 0.7448 1.3427 Fss = 2114273 slope (hr“) = 1.48 D (m2.s'1) = 1.81E-13 r2 = 0.9855 Sample : Nylon 6 1.65 mil Test temperature 60°C Relative humidity 65% Sample no. 2 t (hours) F, (pg.m'2.day") Ft/Fss X 1/X 0.31 81799.10 0.4431 1.9660 0.5087 0.47 135274.30 0.7327 1.2275 0.8147 0.64 159263.30 0.8626 0.9214 1.0854 0.81 171359.30 0.9282 0.7418 1.3482 F... = 1846223 slope (hr’1) = 1.67 D (m2.s") = 2.04E-13 r2 = 0.9987 90 Sample : Nylon 6 1.65 mil Test temperature 60°C Relative humidity 80% Sample no. 1 t (hours) Ft(H9°m-2-day-1) FJFss x W 0.00 0.00 0.0000 33.2855 0.0300 0.38 291206.00 0.8162 1.0339 0.9672 0.55 342970.00 0.9613 0.6253 1.5992 Fss = 356764 slope (hr") = 2.78 D (m2.s") = 3.39E-13 r2 = 0.9875 Sample : Nylon 6 1.65 mil Test temperature 60°C Relative humidity 80% Sample no. 2 t (hours) Fr (99.m‘2.day") Ft/Fss x 1/X 0.00 0.00 0.0000 33.2855 0.0300 0.19 225349.00 0.5672 1.6231 0.6161 0.35 359456.00 0.9048 0.8104 1.2340 F...- = 397275 slooe (hr“) = 3.45 D We") = 4.21E-13 r2 = 0.9984 91 Sample : Blend 1.81 mil Test temperature 60°C Relative humidity 0% Sample no. 1 t (hours) Fr (pg-m'z-day") Ft/Fss x 1Ix 4.28 208.894 0.1125 3.6454 0.2743 4.78 276.378 0.1489 3.3184 0.3013 5.28 334.865 0.1804 3.0910 0.3235 5.78 435.960 0.2348 2.7729 0.3606 6.28 518.176 0.2791 2.5602 0.3906 6.78 591.483 0.3186 2.3944 0.4176 7.28 662.938 0.3571 2.2490 0.4446 7.78 754.593 0.4064 2.0806 0.4806 8.28 806.203 0.4342 1.9929 0.5018 8.78 875.273 0.4714 1.8821 0.5313 9.28 943.553 0.5082 1 .7788 0.5622 9.78 1003.00 0.5402 1.6929 0.5907 10.28 1160.34 0.6250 1.4800 0.6757 10.78 1113.80 0.5999 1.5412 0.6488 11.28 1184.02 0.6377 1.4494 0.6900 11.78 1271.18 0.6847 1.3386 0.7471 12.28 1257.59 0.6773 1.3557 0.7376 12.78 1295.00 0.6975 1.3088 0.7641 13.28 1345.72 0.7248 1.2457 0.8028 13.78 1396.80 0.7523 1.1824 0.8458 14.28 1419.76 0.7647 1.1539 0.8666 14.78 1464.63 0.7889 1.0980 0.9107 15.28 1506.45 0.8114 1.0454 0.9566 15.78 1483.25 0.7989 1.0747 0.9305 16.28 1526.53 0.8222 1.0192 0.9811 16.78 1578.34 0.8501 0.9515 1.0510 17.28 1597.54 0.8604 0.9256 1.0804 17.78 1628.10 0.8769 0.8832 1.1323 Fss = 1856.66 slope (hr") = 0.06 D (m2.s") = 9045-15 r2 = 0.9950 92 Sample : Blend 1.81 mil Test temperature 60°C Relative humidity 0% Sample no. 2 t (hours) Fr (09.m'2-day") Ft/Fss x 1/X 4.77 255.30 0.1382 3.4053 0.2937 5.27 319.96 0.1733 3.1388 0.3186 5.77 409.67 0.2218 2.8420 0.3519 6.27 477.69 0.2587 2.6542 0.3768 6.77 551.26 0.2985 2.4763 0.4038 7.27 615.92 0.3335 2.3362 0.4280 7.77 711.90 0.3855 2.1498 0.4651 8.27 781.15 0.4230 2.0278 0.4931 8.77 849.60 0.4601 1.9152 0.5221 9.27 915.41 0.4957 1.8133 0.5515 9.77 960.04 0.5199 1.7471 0.5724 10.27 1033.97 0.5599 1.6418 0.6091 10.77 1083.10 0.5865 1.5745 0.6351 11.27 1150.41 0.6230 1.4849 0.6735 11.77 1230.42 0.6663 1.3816 0.7238 12.27 1223.10 0.6623 1.3909 0.7189 12.77 1263.24 0.6841 1.3400 0.7463 13.27 1307.17 0.7078 1.2848 0.7783 13.77 1348.90 0.7304 1.2327 0.8112 14.27 1369.63 0.7417 1.2069 0.8286 14.77 1417.97 0.7678 1.1466 0.8721 15.27 1450.29 0.7853 1.1061 0.9040 15.77 1465.08 0.7934 1.0875 0.9195 16.27 1504.33 0.8146 1.0378 0.9636 16.77 1548.62 0.8386 0.9805 1.0199 17.27 1565.82 0.8479 0.9579 1.0440 17.77 1576.14 0.8535 0.9441 1.0592 18.27 1616.45 0.8753 0.8892 1.1246 18.77 1607.28 0.8704 0.9019 1.1088 F0 = 1846.69 slope (hr'1) = 0.06 D (m2.s") = 8.74E-15 r2 = 0.9975 93 Sample : Blend 1.81 mil Test temperature 60°C Relative humidity 35% Sample no. 1 t (hours) Ft (rig-mafia") Ft/Fss x 1/x 0.52 724.590 0.0270 5.2551 0.1903 0.68 2160.31 0.0805 4.0299 0.2481 0.85 3959.72 0.1476 3.3284 0.3004 1.02 5857.92 0.2184 2.8611 0.3495 1.18 7960.12 0.2967 2.4838 0.4026 1.35 9864.72 0.3677 2.2111 0.4523 1.52 11879.9 0.4428 1.9666 0.5085 1.68 13613.5 0.5075 1.7808 0.5616 1.85 15240.1 0.5681 1.6209 0.6170 2.02 16944.9 0.6317 1.4639 0.6831 2.18 18003.5 0.6711 1.3703 0.7298 2.35 19173.1 0.7147 1.2689 0.7881 2.52 20363.7 0.7591 1.1668 0.8571 2.68 21277.7 0.7932 1.0880 0.9191 2.85 22258.2 0.8297 1.0019 0.9981 3.02 22762.0 0.8485 0.9564 1.0456 3.18 23015.7 0.8579 0.9331 1.0717 3.35 23506.7 0.8763 0.8868 1 .1277 3.52 24251.4 0.9040 0.8126 1.2307 Fss = 26826.4 slope (hr") = 0.34 D (m2.s") = 5.01E-14 r2 = 0.9979 94 Sample : Blend 1.81 mil Test temperature 60°C Relative humidity 35% Sample no. 2 t (hours) Fr (ug-m‘2.day") Ft/Fss x 1/X 0.72 576.5 0.0270 5.2574 0.1902 0.88 1549.8 0.0725 4.1502 0.2410 1.05 2451.8 0.1146 3.6237 0.2760 1.22 3724.9 0.1742 3.1326 0.3192 1 .38 5089.8 0.2380 2.7565 0.3628 1 .55 6253.5 0.2924 2.5022 0.3997 1.72 7414.5 0.3467 2.2869 0.4373 1 .88 8730.6 0.4082 2.0749 0.4820 2.05 9853.0 0.4607 1.9134 0.5226 2.22 10828.2 0.5063 1.7840 0.5605 2.38 11909.2 0.5568 1.6497 0.6062 2.55 12952.0 0.6056 1.5272 0.6548 2.72 13807.0 0.6456 1.4306 0.6990 2.88 14595.2 0.6824 1.3438 0.7441 3.05 15280.2 0.7144 1.2696 0.7877 3.22 15743.9 0.7361 1.2196 0.8199 3.38 16390.1 0.7663 1.1501 0.8695 3.55 16888.6 0.7896 1.0962 0.9123 3.72 17263.9 0.8072 1.0552 0.9477 3.88 17826.1 0.8335 0.9928 1.0072 4.05 18123.1 0.8474 0.9592 1.0426 4.22 18490.8 0.8646 0.9166 1.0910 4.38 18924.6 0.8848 0.8644 1.1568 4.55 19038.9 0.8902 0.8503 1.1761 F0 = 21387.6 slope (hr'1) = 0.26 D (m2.s'1) = 3.79E-14 r2 = 0.9993 95 Sample : Blend 1.81 mil Test temperature 60°C Relative humidity 50% Sample no. 1 t (hours) Ft (Ito-m'zday") Ft/Fss x 1/X 0.78 4073.96 0.0981 3.8032 0.2629 0.94 7475.26 0.1801 3.0929 0.3233 1.11 10821.56 0.2607 2.6446 0.3781 1.28 14823.86 0.3571 2.2489 0.4447 1.44 17577.56 0.4234 2.0264 0.4935 1.61 20445.46 0.4925 1.8222 0.5488 1 .78 23087.36 0.5562 1.6515 0.6055 1.94 25769.76 0.6208 1.4902 0.671 1 2.1 1 27639.36 0.6658 1.3827 0.7232 2.28 29523.66 0.7112 1.2770 0.7831 2.44 30927.36 0.7450 1.1991 0.8339 2.61 32178.16 0.7752 1.1297 0.8852 2.78 34191.56 0.8237 1.0163 0.9839 2.94 34331.36 0.8270 1.0083 0.9918 3.1 1 35028.06 0.8438 0.9679 1.0332 3.44 37209.06 0.8963 0.8337 1.1995 Fss = 41511.86 slope (hr'1) = 0.34 D (m2.s") = 5.035-14 r2 = 0.9974 96 Sample : Blend 1.81 mil Test temperature 60°C Relative humidity 50% Sample no. 2 t (hours) F. (ug-m'2.day") PIP.- x 1lX 0.14 0.00 0.0000 33.2855 0.0300 0.31 1136.82 0.0220 5.4832 0.1824 0.47 4484.02 0.0866 3.9465 0.2534 0.64 10030.52 0.1938 3.0051 0.3328 0.81 16008.72 0.3093 2.4318 0.4112 0.97 21431.02 0.4140 2.0562 0.4863 1.14 26175.52 0.5057 1.7856 0.5600 1.31 30766.72 0.5944 1.5548 0.6432 1.47 34481.82 0.6662 1.3819 0.7236 1.64 38280.62 0.7396 1.2117 0.8253 1.81 40353.62 0.7796 1.1194 0.8933 1.97 43544.72 0.8413 0.9741 1.0266 2.14 44686.32 0.8633 0.9197 1.0873 2.31 45513.82 0.8793 0.8789 1.1378 2.47 46967.82 0.9074 0.8031 1.2452 2.64 47807.52 0.9236 0.7557 1.3232 2.81 48528.22 0.9375 0.7118 1.4048 F..- = 51761.72 sl0pe (hr") = 0.50 D (m2.s") = 7.3699E-14 r2 = 0.9981 97 Sample : Blend 1.81 mil Test temperature 60°C Relative humidity 65% Sample no. 1 t (hours) Fr (rig-m'z-daY") Ft/Fss x 1IX 0.36 15779.4 0.1557 3.2652 0.3063 0.52 34382.6 0.3393 2.3143 0.4321 0.69 51473.8 0.5080 1.7793 0.5620 0.86 65150.3 0.6430 1.4368 0.6960 1.02 76319.2 0.7532 1.1803 0.8472 1.19 82737.4 0.8165 1.0332 0.9679 1.36 89152.0 0.8798 0.8775 1.1396 F0 = 101327 slope (hr") = 0.83 D (m2.s") = 1.215-13 r2 = 0.9983 Sample : Blend 1.81 mil Test temperature 60°C Relative humidity 65% Sample no. 2 t (hours) F1 (Ito-r0490") FIFss x 1lX 0.36 13303.4 0.1274 3.5007 0.2857 0.53 40824.9 0.3910 2.1314 0.4692 0.69 55228.8 0.5290 1 .7227 0.5805 0.86 67970.7 0.6510 1.4177 0.7054 1.03 77871.1 0.7458 1.1973 0.8352 1.19 85493.0 0.8188 1.0278 0.9729 1.36 92396.0 0.8849 0.8642 1.1571 Fss = 104411 slope (hr") = 0.83 D (m2.s") = 1.225-13 r2 = 0.9950 98 Sample : Blend 1.81 mil Test temperature 60°C Relative humidity 80% Sample no. 1 Ft (ug.m'2.day'1) t (hours) Ft/Fss x 1/X 0.18 36000 0.2399 2.7469 0.3641 0.34 77700 0.5177 1.7530 0.5705 0.50 121072 0.8067 1.0564 0.9466 F0 = 150089 slope (hr'1) = 1.84 D (m2.s") = 2.705-13 r2 = 0.9808 Sample : Blend 1.81 mil Test temperature 60°C Relative humidity 80% Sample no. 2 t (hours) 5 00.02.00") PIP... x 1/X 0.33 47485.5 0.3035 2.4554 0.4073 0.42 71231.7 0.4553 1.9294 0.5183 0.58 102038 0.6522 1.4149 0.7068 0.75 121488 0.7765 1.1266 0.8876 0.92 137622 0.8796 0.8781 1.1389 Fss = 156456 slope (hr'1) = 1.22 D (m2.s'1) = 1.795-13 r2 = 0.9962 99 Sample : Selar PA 1.70 mil Test temperature 60°C Relative humidity 0% Sample no. 1 t (hours) Fr (us-m'Z-daY") Ft/Fss x W 3.80 32.02 0.0162 5.8153 0.1720 4.13 40.14 0.0203 5.5677 0.1796 4.46 67.31 0.0341 4.9966 0.2001 4.80 74.54 0.0378 4.8830 0.2048 5.13 162.58 0.0824 4.0040 0.2498 5.46 196.10 0.0994 3.7889 0.2639 5.80 248.86 0.1261 3.5129 0.2847 6.13 289.17 0.1465 3.3371 0.2997 6.46 341.75 0.1732 3.1395 0.3185 6.80 391.85 0.1986 2.9759 0.3360 7.13 430.93 0.2184 2.8612 0.3495 7.46 462.60 0.2344 2.7750 0.3604 7.80 536.88 0.2720 2.5920 0.3858 8.13 586.19 0.2970 2.4825 0.4028 8.46 620.51 0.3144 2.4110 0.4148 8.80 660.20 0.3345 2.3324 0.4287 9.13 694.43 0.3519 2.2678 0.4409 9.46 769.33 0.3898 2.1353 0.4683 9.80 796.20 0.4034 2.0903 0.4784 10.13 825.51 0.4183 2.0426 0.4896 10.46 878.44 0.4451 1.9598 0.5103 10.80 926.26 0.4693 1.8882 0.5296 11.13 939.66 0.4761 1.8686 0.5352 11.46 994.71 0.5040 1.7902 0.5586 11.80 1031.50 0.5227 1.7396 0.5749 12.13 1062.02 0.5381 1.6984 0.5888 12.46 1095.10 0.5549 1.6547 0.6043 12.80 1128.89 0.5720 1.6109 0.6208 13.13 1175.82 0.5958 1.5514 0.6446 13.46 1211.72 0.6140 1.5067 0.6637 13.80 1242.77 0.6297 1.4686 0.6809 14.13 1253.98 0.6354 1.4549 0.6873 14.46 1288.82 0.6530 1.4129 0.7078 14.80 1312.90 0.6652 1.3840 0.7225 15.13 1344.75 0.6814 1.3462 0.7428 15.46 1362.39 0.6903 1.3254 0.7545 15.80 1378.98 0.6987 1.3059 0.7658 16.13 1415.85 0.7174 1.2627 0.7920 100 Ft (ug.m'2.day'1) t (hours) Ft/Fss X 1lX 16.46 1430.14 0.7247 1.2460 0.8026 16.80 1448.67 0.7340 1.2244 0.8167 17.13 1455.02 0.7373 1.2170 0.8217 17.46 1476.54 0.7482 1.1919 0.8390 17.80 1494.80 0.7574 1.1706 0.8542 18.13 1524.44 0.7724 1.1360 0.8803 18.46 1546.50 0.7836 1.1102 0.9008 18.80 1544.03 0.7824 1.1131 0.8984 19.13 1568.55 0.7948 1.0842 0.9223 19.46 1575.43 0.7983 1.0761 0.9293 19.80 1589.37 0.8053 1.0596 0.9438 20.13 1602.16 0.8118 1.0443 0.9575 F0 = 1973.554 slope (hr“) = 0.05 D (m2.s") = 6.27E-15 r2 = 0.9986 101 Sample : Selar PA 1.70 mil Test temperature 60°C Relative humidity 0% Sample no. 2 102 t (hours) Ft (us-m'z-day") Ft/Fss x 1IX 6.47 235.71 0.1224 3.5475 0.2819 6.80 283.08 0.1470 3.3332 0.3000 7.13 347.30 0.1803 3.0911 0.3235 7.47 387.00 0.2010 2.9614 0.3377 7.80 427.67 0.2221 2.8407 0.3520 8.13 459.95 0.2388 2.7520 0.3634 8.47 507.24 0.2634 2.6319 0.3800 8.80 564.14 0.2929 2.4998 0.4000 9.13 618.57 0.3212 2.3840 0.4195 9.47 652.00 0.3386 2.3171 0.4316 9.80 681.11 0.3537 2.2612 0.4422 10.13 753.54 0.3913 2.1304 0.4694 10.47 775.06 0.4025 2.0935 0.4777 10.80 825.69 0.4288 2.0098 0.4976 11.13 843.69 0.4381 1.9810 0.5048 11.47 888.50 0.4614 1.9114 0.5232 11.80 915.06 0.4752 1.8713 0.5344 12.13 925.11 0.4804 1.8564 0.5387 12.47 976.81 0.5072 1.7814 0.5614 12.80 1017.21 0.5282 1.7247 0.5798 13.13 1069.35 0.5553 1.6537 0.6047 13.47 1093.96 0.5681 1.6209 0.6169 13.80 1101.63 0.5721 1.6108 0.6208 14.13 1158.44 0.6016 1.5371 0.6506 14.47 1173.79 0.6095 1.5176 0.6590 14.80 1207.14 0.6268 1.4755 0.6777 15.13 1238.45 0.6431 1.4365 0.6961 15.47 1267.48 0.6582 1.4007 0.7139 15.80 1290.77 0.6703 1.3722 0.7287 16.13 1290.15 0.6700 1.3730 0.7283 16.47 1335.23 0.6934 1.3184 0.7585 16.80 1348.11 0.7000 1.3028 0.7676 17.13 1392.04 0.7229 1.2501 0.7999 17.47 1405.80 0.7300 1.2337 0.8106 17.80 1408.62 0.7315 1.2303 0.8128 18.13 1412.15 0.7333 1.2261 0.8156 18.47 1447.96 0.7519 1.1833 0.8451 18.80 1471.52 0.7641 1.1552 0.8657 F, (ug.m'2.day") t (hours) Ft/Fss X 1/X 19.13 1483.78 0.7705 1.1405 0.8768 19.47 1489.96 0.7737 1.1331 0.8826 19.80 1508.57 0.7834 1.1107 0.9003 20.13 1523.12 0.7909 1.0932 0.9148 20.47 1540.59 0.8000 1.0720 0.9328 20.80 1543.85 0.8017 1.0681 0.9362 21.13 1539.09 0.7992 1.0739 0.9312 21.47 1554.97 0.8075 1.0546 0.9483 F..- = 1925.74 slope (hr“) = 0.05 D (m2.s") = 5.89E-15 r2 = 0.9978 103 Sample : Selar PA 1.70 mil Test temperature 60°C Relative humidity 35% Sample no. 1 t (hours) F, (HQ-miz-day'” Ft/Fss X 1/X 1.36 115.90 0.0191 5.6380 0.1774 1.69 237.77 0.0391 4.8435 0.2065 1 .86 352.28 0.0580 4.4026 0.2271 2.02 474.23 0.0781 4.0655 0.2460 2.19 605.41 0.0996 3.7856 0.2642 2.36 746.68 0.1229 3.5428 0.2823 2.52 851.42 0.1401 3.3894 0.2950 2.69 969.86 0.1596 3.2360 0.3090 2.86 1139.03 0.1875 3.0447 0.3284 3.02 1338.66 0.2203 2.8502 0.3508 3.19 1478.97 0.2434 2.7288 0.3665 3.36 1626.68 0.2677 2.6116 0.3829 3.52 1790.84 0.2948 2.4921 0.4013 3.86 2123.17 0.3495 2.2766 0.4392 4.02 2287.68 0.3765 2.1804 0.4586 4.19 2527.22 0.4160 2.0500 0.4878 4.36 2759.55 0.4542 1.9325 0.5175 4.69 3025.41 0.4980 1.8070 0.5534 4.86 3208.20 0.5281 1.7251 0.5797 5.02 3309.81 0.5448 1.6810 0.5949 5.19 3489.29 0.5743 1.6051 0.6230 5.42 3611.34 0.5944 1.5548 0.6432 5.62 3843.82 0.6327 1.4614 0.6843 5.81 3956.53 0.6512 1.4172 0.7056 6.01 4073.15 0.6704 1.3719 0.7289 6.21 4141.83 0.6817 1.3454 0.7433 6.41 4256.50 0.7006 1.3016 0.7683 6.61 4345.30 0.7152 1.2678 0.7888 6.81 4437.18 0.7303 1.2329 0.8111 7.00 4550.51 0.7490 1.1900 0.8403 7.20 4606.36 0.7582 1.1689 0.8555 7.40 4690.96 0.7721 1.1368 0.8797 7.60 4775.55 0.7860 1.1045 0.9053 7.80 4802.67 0.7905 1.0942 0.9139 8.00 4909.43 0.8081 1.0531 0.9495 8.19 4969.49 0.8180 1.0298 0.9710 8.39 5029.56 0.8278 1 .0063 0.9937 8.59 5060.89 0.8330 0.9940 1.0060 104 Fr (09-m'2-day") t (hours) FIIFss X 1/X 8.79 5092.21 0.8382 0.9816 1.0188 8.99 5178.14 0.8523 0.9471 1.0559 9.19 5241.08 0.8627 0.9213 1.0854 9.39 5272.41 0.8678 0.9083 1.1009 9.58 5332.47 0.8777 0.8830 1.1325 9.78 5392.54 0.8876 0.8572 1.1666 9.98 5423.87 0.8927 0.8434 1.1857 10.18 5455.20 0.8979 0.8294 1.2057 F0 = 6075.50 slope (hr'1) = 0.12 D (m2.s") = 1.535-14 r2 = 0.9990 105 Sample : Selar PA 1.70 mil Test temperature 60°C Relative humidity 35% Sample no. 2 t (hours) 1:, (000290") FIF... x 17x 2.04 601.95 0.1008 3.7724 0.2651 2.21 742.41 0.1243 3.5294 0.2833 2.37 846.55 0.1418 3.3759 0.2962 2.54 964.32 0.1615 3.2224 0.3103 2.71 1132.52 0.1896 3.0310 0.3299 2.87 1331.01 0.2229 2.8363 0.3526 3.04 1470.52 0.2462 2.7147 0.3684 3.21 1617.38 0.2708 2.5974 0.3850 3.37 1780.61 0.2982 2.4777 0.4036 3.71 2111.04 0.3535 2.2619 0.4421 3.87 2274.61 0.3809 2.1655 0.4618 4.04 2512.78 0.4208 2.0348 0.4915 4.21 2743.78 0.4595 1.9170 0.5216 4.54 3008.12 0.5037 1.7911 0.5583 4.71 3189.87 0.5342 1.7089 0.5852 4.87 3290.89 0.5511 1.6646 0.6007 5.04 3469.35 0.5810 1.5884 0.6296 5.26 3590.71 0.6013 1.5378 0.6503 5.46 3821.86 0.6400 1.4439 0.6926 5.66 3933.92 0.6588 1.3994 0.7146 5.86 4049.87 0.6782 1.3537 0.7387 6.06 4118.17 0.6896 1.3271 0.7535 6.26 4232.17 0.7087 1.2828 0.7795 6.46 4320.47 0.7235 1.2487 0.8008 6.65 4411.82 0.7388 1.2135 0.8241 6.85 4524.50 0.7576 1.1701 0.8546 7.05 4580.04 0.7669 1 .1487 0.8706 7.25 4664.15 0.7810 1.1161 0.8959 7.45 4748.26 0.7951 1.0834 0.9230 7.65 4775.23 0.7996 1.0729 0.9321 7.84 4881.37 0.8174 1.0311 0.9698 8.04 4941.09 0.8274 1.0074 0.9927 8.24 5000.82 0.8374 0.9834 1.0169 8.44 5031.97 0.8426 0.9707 1.0301 8.64 5063.12 0.8478 0.9580 1.0438 8.84 5148.55 0.8621 0.9226 1.0839 9.03 5211.13 0.8726 0.8961 1.1160 9.23 5242.28 0.8778 0.8827 1.1329 9.43 5302.00 0.8878 0.8565 1.1676 9.63 5361.72 0.8978 0.8296 1.2054 106 F.- = 5971.78 slope (hr'1) = 0.12 D (m2.s") = 1.60E-14 r2 = 0.9989 107 Sample : Selar PA 1.70 mil Test temperature 60°C Relative humidity 50% Sample no. 1 t (hours) F, (HQ-"1-2931(4) Ft/Fss X 1/X 1.15 549.012 0.0675 4.2305 0.2364 1.31 779.204 0.0958 3.8307 0.2610 1.48 1288.59 0.1585 3.2447 0.3082 1.65 1656.47 0.2037 2.9451 0.3395 1 .81 2076.32 0.2553 2.6702 0.3745 1.98 2370.36 0.2915 2.5060 0.3990 2.15 2951.97 0.3630 2.2277 0.4489 2.31 3332.24 0.4098 2.0698 0.4831 2.48 3714.82 0.4568 1.9248 0.5195 2.65 4171.86 0.5130 1.7656 0.5664 2.81 4446.47 0.5468 1.6757 0.5968 2.98 4627.74 0.5691 1.6184 0.6179 3. 31 5072.55 0.6238 1.4829 0.6744 3.48 5446.59 0.6698 1.3734 0.7281 3.65 5810.82 0.7146 1.2692 0.7879 3.81 5847.40 0.7191 1.2589 0.7944 4.15 6010.93 0.7392 1.2126 0.8247 4.31 6255.59 0.7693 1.1433 0.8747 4.48 6391.59 0.7860 1.1046 0.9053 4.65 6593.36 0.8108 1.0467 0.9554 4.88 6861 .90 0.8438 0.9678 1 .0333 5.09 6967.52 0.8568 0.9359 1 .0685 F53 = 8131.82 slope (hr") = 0.21 D (m2.s") = 2685-14 r2 = 0.9964 108 Sample : Selar PA 1.70 mil Test temperature 60°C Relative humidity 50% Sample no. 2 t (hours) Ft (“Q-"1-2931(4) F,lFss X 1/X 0.55 30.73 0.0038 7.3841 0.1354 0.72 85.13 0.0105 6.2847 0.1591 0.89 68.24 0.0085 6.5245 0.1533 1.25 232.05 0.0288 5.1858 0.1928 1.58 702.86 0.0871 3.9403 0.2538 1.75 1048.43 0.1299 3.4780 0.2875 1.91 1596.28 0.1978 2.9804 0.3355 2.08 1964.17 0.2434 2.7289 0.3664 2.25 2345.55 0.2907 2.5096 0.3985 2.41 2678.05 0.3319 2.3426 0.4269 2.58 3067.36 0.3801 2.1682 0.4612 2.75 3332.24 0.4129 2.0597 0.4855 2.91 3714.82 0.4603 1.9144 0.5223 3.08 4171.86 0.5170 1.7549 0.5698 3.25 4446.47 0.5510 1.6648 0.6007 Fss = 8069.74 slope (hr") = 0.18 D (m2.s") = 2.315-14 r2 = 0.9838 109 Sample : Selar PA 1.70 mil Test temperature 60°C Relative humidity 65% Sample no. 1 t (hours) Ft (09-m'2-day") Ft/Fss x W 0.50 1389.35 0.0631 4.3073 0.2322 0.67 3455.84 0.1569 3.2562 0.3071 0.83 5942.76 0.2698 2.6020 0.3843 1.00 8430.23 0.3828 2.1590 0.4632 1.17 10500.3 0.4768 1.8667 0.5357 1.33 12530.7 0.5690 1.6186 0.6178 F.- = 22022.52 slope (hr") = 0.46 D (m2.s") = 5.98E-14 r2 = 0.9998 Sample : Selar PA 1.70 mil Test temperature 60°C Relative humidity 65% Sample no. 2 t (hours) Ft (ug.m'2.day'1) Ft/Fss X “X 0.25 103.88 0.0038 7.3954 0.1352 0.42 1725.66 0.0626 4.3160 0.2317 0.59 3480.66 0.1263 3.5112 0.2848 0.94 9884.33 0.3586 2.2435 0.4457 1.28 15635.66 0.5672 1.6230 0.6161 1.44 18233.71 0.6615 1.3929 0.7179 1.61 19695.43 0.7145 1.2694 0.7878 1.78 21198.88 0.7691 1.1438 0.8743 1.94 22357.96 0.8111 1.0460 0.9561 2.11 23221.81 0.8425 0.9711 1.0297 2.28 24277.67 0.8808 0.8751 1.1427 2.44 24912.98 0.9038 0.8131 1.2299 F..- = 27564.2 slope (hr‘) = 0.49 D (m2.s“) = 6415-14 r2 = 0.9983 110 Sample : Selar PA 1.70 mil Test temperature 60°C Relative humidity 80% Sample no. 1 t (hours) F, (Pg-m'Z-daYJ) Ft/Fss X 1/X 0.50 9843.90 0.1552 3.2692 0.3059 0.67 18755.70 0.2957 2.4880 0.4019 0.83 28033.10 0.4420 1.9692 0.5078 1.00 37194.90 0.5865 1.5746 0.6351 1.46 49525.50 0.7809 1.1 165 0.8957 1.63 52518.90 0.8281 1.0058 0.9943 1.79 55162.50 0.8698 0.9034 1.1069 1.96 56818.50 0.8959 0.8349 1.1977 Fss = 63422.3 slope (hr") = 0.61 D (m2.s") = 7.955-14 r2 = 0.9993 Sample : Selar PA 1.70 mil Test temperature 60°C Relative humidity 80% Sample no. 2 t (hours) Ft (09-m‘2.day“) FIE-.- x 1Ix 0.37 8533.60 0.1330 3.4510 0.2898 0.54 19033.09 0.2965 2.4846 0.4025 0.70 29853.16 0.4651 1.9005 0.5262 0.87 37974.85 0.5916 1.5617 0.6403 1.04 45784.78 0.7133 1.2722 0.7861 1.20 50779.33 0.7911 1.0927 0.9152 F..- = 64185.82 slope (hr'1) = 0.75 D (m2.s") = 9.755-14 r2 = 0.9983 111 BIBLIOGRAPHY 112 BIBLIOGRAPHY Ashley, R. J. (1985). "Permeability And Plastics Packaging," Ch. 7, in Polymer Penneability, J. Comyn, Ed., Elsevier Applied Science, Essex, England. ASTM E 1356-98. (1999). "Standard Test method for Assignment of the Glass Transition Temperatures by Differential Scanning Calorimetry or Differential Thermal Analysis," in 1999 Annual Book of ASTM Standards, 15.09: 498-501. ASTM F 1769-97 (1999). "Standard Test Method for Measurement of Diffusivity, Solubility, and Permeability of Organic Vapor Barriers Using a Flame Ionization Detector," in 1999 Annual Book of ASTM Standards, 15.09: 1401-1407. Baner, A. L., Hernandez, R. J., Jayaraman, K., and Giacin, J. R. (1986). "lsostatic and Quasi-lsostatic Methods for Determining the Permeability of Organic Vapors through Barrier Membranes," in Current Technologies in Flexible Packaging: ASTM STP, 912, M. L. Troedel, ed., ASTM, Philadelphia. Berens, A. R. and Hopfenberg, H. B. (1982). "Diffusion of Organic Vapors at Low Concentrations in Glassy PVC, Polystyrene and PMMA," J. Memb. Sci., 10 (2-3): 283. BASF. (1995). “Product lnfon'nation Sheets: Ultramid,” BASF Corporation: Plastic Materials, New Jersey. Billmeyer, F. W. (1984). Textbook of Polymer Science, erey-lnterscience, New York. Blatz, P. (1989). "Properties of Films from Blends of Amorphous and Semicrystalline Nylons," American Institute of Chemical Engineering National Conference, April 26, Houston, Texas. Briston, J. H. (1986). "Films, Plastics," pp. 330 in The Wiley Encyclopedia of Packaging Technology. M. Bakker, Ed., John Wiley 8 Sons, New York. Briston, J. H. (1988). Plastic Films, Longman Scientific & Technical, Essex, England. Brydson, J. A. (1982). Plastics Maten'als, 4th ed., Butterworth Scientific, Essex, England. 113 Chem, R. T., Koros, W. J., Sanders, E. S., and Yui, R. (1983). "Second Component: Effect in Sorption and Permeation in Glassy Polymers," J. Membrane Sci., 15: 157-169. Crank, J. (1975). The Mathematics of Difiusions, 2nd ed., Clarendon Press, Oxford, England. Crank, J. and Park, G. S. (1968). Diffusion in Polymers, Academic Press, New York. DeLassus, P. T., Strandburg, G., and Howell, B. A. (1988). "Flavor and Aroma Permeation in Barrier Film: the Effects of High Temperature and High Humidity," TAPPI J., 71(11): 177-181 Demorest, R. L and Mayer, D. W. (1996). "Advanced Measuring Methods Enhance WVTR Testing: Part I," Packaging Technology & Engineering, pp. 41-44. DuPont. (1996a). "Selar PA 3426," (Online), E. l. du Pont de Nemours and Co., Available: http://www.dupont.com/packaging/products/resins/E-92121 IE- 92121.html. DuPont. (1996b). "Selar PA 3426, Blends with Nylon 6," (Online), E. I. du Pont de Nemours and Co., Available: http://www.dupont.com/packaging/productslresins/ H-26598-2/H-26598-2.html. Flory, P. J. (1953). Principles of Polymer Chemistry, Cornell University Press, Ithaca, NY. Foster, R. H. (1991). "Barrier Packaging Technologies: What Are The Altematives?," 8th Annual Food Plas Conference, March 5-7, Orlando, Florida. Fox, D. W. and Allen, R. B. (1985). "Compatibility," in Encyclopedia of Polymer Science and Engineering, Vol. 3, John Wiley & Sons, New York. Gavara, R. and Hernandez, R. J. (1993). "Consistency Test for Continuous Flow Permeability Experimental Data," J. Plastic Film & Sheeting, 9: 126-138. Giacin, J. R. and Hernandez, R. J. (1997). "Permeability of Aromas and Solvents in Polymeric Packaging Materials," in The WIIey Encyclopedia of Packaging Technology, A. L. Brody and K. S. Marsh, eds., Wiley, New York. 114 Gilbert, S. G., Hatzidimitriu, E. Lai, C., and Passey, N. (1983). "The Study of Barrier Properties of Polymeric Films to Various Organic Aromatic Vapors," Instrumental Analysis of Foods, 1:405. Gottfried, B. S. (1998). Spreadsheet Tools for Engineers: Excel 97 Version, McGraw-Hill, New York, NY. Greenspan, L. (1977) "Humidity Fixed Points of Binary Saturated Aqueous Solutions," Journal of Research of the National Bureau of Standards-A. Physics and Chemistry, 81A(1):89-96. Harris, J. E., and Merriam, N. (1988). "Blends and Alloys of Engineering Plastics," pp.632-637 in Engineered Materials Handbook, Vol. 2, ASM International, Metals Park, Ohio. Hatakeyama, T. and F. X. Quinn. (1999). "Thermal Analysis: Fundamentals and Applications to Polymer Science," 2nd ed., John \Mley & Sons Ltd., West Sussex, England. Hernandez, R. J. (1989). "Modeling the Sorption of Water, and the Effect of Sorbed Water on the Solubility and Diffusivity of Oxygen in an Amorphous Polyamide," Doctoral Dissertation, Michigan State University, E. Lansing, MI. Hernandez, R. J. (1994). "Effect of Water Vapor on the Transport Properties of Oxygen through Polyamide Packaging Materials," J. Food Engineering, 22: 495—507. Hernandez, R. J. (1996). "Plastics in Packaging," Ch. 8 in Handbook of Plastics, Elastomers, and Composites, 3rd ed., C.A. Harper, Ed., McGraw-Hill, New York. Hernandez, R. J.,Giacin, J. R., and Grulke, E. A. (1992). "The Sorption of Water Vapor by An Amorphous Polyamide," J. Membrane Sci., 65: 187-199. Hernandez, R. J., Giacin, J. R. and Baner, L. (1986). "The Evaluation of the Aroma Barrier Properties of polymer films," J. Plastic Film & Sheeting. 2: 187-211. Huang, S. J. and Giacin, J. R. (1998). "Evaluating the Effect of Temperature and Vapor Concentration on the Organic Vapor Barrier Properties of Polymer Membranes by an lsostatic Procedure," J. Plastic Film & Sheeting, 14 (4): 308-333. Ito, Y. (1961). "Effect of Water Vapor on Permeation of Gases through Hydrophilic Polymers". Chem. High. Polym., 18: 158. 115 Jabarin, S. A. and Lofgren, E. A. (1986). "Effects of Water-Absorption on Physical- Properties of High Nitrile Barn'er Polymers," Polym. Eng. Sci. 26 (6): 405. Khanna, Y. P., Day, E. D., Tsai, M. L., and Vaidyanathan, G. (1997). "Re-Examining the Oxygen Barrier of Nylon 6 Films. I. Role of Moisture and Processing Induced Variables," J. Plastic Film & Sheeting, 13(3): 197-211. Khanna, Y. P., Kuhn W. P., and Sichina, W. J. (1995). "Reliable Measurements of the Nylon 6 Glass Transition Made Possible by the New Dynamic DSC," Macromolecules, 28: 2644-2646. Khanna, Y. P. and Kuhn, W. P. (1997). "Measurement of Crystalline Index in Nylons by DSC: Complexities and Recommendations," J. Polym. Sci: Part B: Polym Phys, 35: 2219-2231. Kienzle, S. Y. (1988). "Properties Modification by Use of Polymer-Polymer Mixtures," pp.487-492 in Engineered Materials Handbook, Vol. 2, ASM lntemational, Metals Park, Ohio. Kirloskar, M. (1991). "Shelf Life Prediction of A Packaged Moisture Sensitive Solid Drug Product Over A Range of Temperature and Relative Humidity Values," Master's Thesis, Michigan State University, E. Lansing, MI. Kohan, M. I. (1988). "Polyamides (PA)," pp.124-127 in Engineered Materials Handbook, Vol. 2, J. N. Epel, J. M. Margolis, S. Newman, and R. B. Seymour, Eds., ASM lntemational, Metals Park, Ohio. Krause, S. (1978). "Polymer-Polymer Compatibility," Ch.2, in Polymer Blends, D. R. Paul and S. Newman, Eds., Academic Press, New York. Lim, L., Britt, I. J., and Tung, MA. (1998). "Sorption and Permeation of Allyl Isothiocyanate Vapor in Nylon 6,6 Film as Affected by Relative Humidity," J. Plastic Film & Sheeting, 14: 207-225. Liu, K. J. (1986). "Evaluation of the Effect of Relative Humidity on the Permeation of Toluene Vapor through Barrier Films," Master’s Thesis, Michigan State University, E. Lansing, MI. Liu, K. J., Hernandez, R. J. and Giacin, J. R. (1991). "The Effect of Water Activity and Penetrant Vapor Activity on the Permeation of Toluene Vapor through a Two- Side PVDC Coated Opaque Oriented Polypropylene Film," J. Plastic Film & Sheeting, 7: 56-67. 116 MacKnight, W.J., Karasz, F. E., and Fried, J. R. (1978). "Solid State Transition Behavior of Blends," Ch. 5 in Polymer Blends, Vol. 1, DR. Paul and S. Newman, Eds., Academic Press, New York. Mark, J. E., Eisenberg, A., Graessley, W. W., Mandelkem, L., and Koenig, J. L. (1984). Physical Properties of Polymers, American Chemical Society, Washington, D. C. Meares, P. (1965). "Transient Permeation of Organic Vapors Through Polymer Membranes," J. Appl. Polym. Sci., 9: 917. Mehta, M. M. (1988). "Test Program Design and Statistical Analysis of Test Data," pp. 599-609 in Engineered Material Handbook, Vol. 2, ASM lntemational, Metals Park, OH. Meyer, J.A., Rogers, C., Stannett, V., and Szwarc, M. (1957). "Studies in the gas and Vapor Permeability of Plastic Films and Coated Papers, Part III. The Permeation of Mixed Vapor and Gases". TAPPI 40:142. Miltz, J. (1992). "Food Packaging," Ch. 13 in Handbook of Food Engineering, D. R. Heldman and D. B. Lund, Eds., M. Dekker, New York. Modern Control. (1996). Aromatran 1A Operator’s Manual, Modern Control Inc., Minneapolis, MN, USA. Nagaraj, S. (1991). The Effect of Temperature and Sorbed Water on the Permeation of Acetone Vapor through Amorphous Polyamide Film. Master's Thesis. Michigan State University, E. Lansing, MI. Niebergall, H., Humeid, A., and Blochl, W. (1978). "Aroma Permeation of Packaging- Foils and Its Determination with Aid of a New Developed Measuring-Apparatus,” LebensmitteI-Wissenschafl & Technologie. 11(1):1-4. Nemphos, S. P., Salame, M., and Steingiser, S. (1978). "Barrier Polymers," pp. 480—506 in Kirk-Othmer Encyclopedia of Chemical Technology, 3rd ed., Vol. 3, M. Grayson and D. Eckroth, eds., John Wiley & Sons, Inc., New York. Odian, G. G. (1991). Principles of Polymerization, Wiley-Interscience, New York. Ohashi, K. (1991). "Modeling the Sorption of Water Vapor by a Semicrystalline Polyamidengpplication of a New Interpretative Sorption Model," Master's Thesis, Michigan State University, E. Lansing, MI. 117 Pasternak, R. A., Schimscheimer, J. F., and Heller, J. (1970). "A Dynamic Approach to Diffusion and Permeation Measurements", J. Polym. Sci., A-2, 8:467. Paul, D. R. (1978). "Background and Perspective," Ch. 1 in Polymer Blends, Vol. 1, DR. Paul and S. Newman, Eds., Academic Press, New York. Paul, D. R., Barlow, J. W, and Keskkula, H. (1988). "Polymer Blends," pp. 399—461 in Encyclopedia of Polymer Science and Engineering, Vol. 12, HF. Mark, N.M. Bikeles, C.G. Overberger, and G. Menges, Eds., Wiley-Interscience, New York. Pye, D. G., Hoehn, H. H., and Panar, M. (1976). "Measurement of Gas Permeability of Polymers II: Apparatus for Permeabilities of Mixed gases and Vapors," J. Appl. Polym. Sci., 20:287 Rogers, C. E. (1985). "Permeation of gases and Vapours in Polymers," Ch. 2 in Polymer Permeability, J. Comyn, Ed., Elsevier Applied Science, Essex, England. Sajiki, T. and Giacin, JR. (1993). "Permeation of Ethyl Acetate Vapor through Silica Deposited Polyethylene Terephthalate Film And Composite Structures," J. Plastic Film & Sheeting, 9: 97-110. Salame, M. (1986). "The Use of Barrier Polymers in Food And Beverage Packaging," J. Plastic Film & Sheeting, 2: 321-334. Schar, W. and Ruegg- M. (1985). "The Evaluation of G.A.B. Constants from Water Vapour Sorption Data,"' LebensmitteI-Vl/Issenschaft & Technologie. 18(4):225- 229. Seeley, D. (1997). "Aroma Barrier Testing," in The lMIey Encyclopedia of Packaging Technology. A. L. Brody and K. S. Marsh, eds., Vlfiley, New York. Seymour, R. B., and Carraher, CE. (1992). Polymer Chemistry: An Introduction, 3rd ed., Marcel Dekker, New York. Sfirakis, A., and Rogers, CE. (1980). "Effects of Sorption Modes on the Transport and Physical-Properties of Nylon-6," Polym. Eng. Sci. 20 (4): 294-299. Shah, V. (1998). Handbook of Plastics Testing Technology, 2nd ed., John Wiley & Sons, New York. 118 Simril, V.L. and Hershberger, A. (1944). "Permeability of Polymeric Films to Gases," Mod. Plast., 22(11):155. Sperling, L. H. (1986). Introduction to Physical Polymer Science, John Wiley & Sons, New York. Stannett, V. and Yasuda, H. (1965). "The Measurement of Gas and Vapor Permeation and Diffusion in Polymer," Ch. 13 in Testing of Polymers, Vol. 1, John Wiley & Sons, New York. TA Instruments. (1998a). "Determination of Polymer Crystallinity by DSC", literature document no. TA-123 in Thermal Analysis & Rheology Applications Library version 2.5, TA Instrument, Inc., New Castle, DE, USA. TA Instruments. (1998b). "Modulated DSC Compendium: Basic Theory & Experimental Conditions," literature document no. TA-210 in Thermal Analysis & Rheology Applications Library version 2. 5, TA Instrument, Inc., New Castle, DE, USA. Torr, H. D. (1995). "Transparent Nylon," pp. 377-387 in Nylon Plastics Handbook, M. l. Kohan, Ed., Hanser/Gardner Publication, Inc., Cincinnati, Ohio. Tubridy, M.F. and Sibilia, J. P. (1986). "Nylon," pp. 477-482 in The Wiley Encyclopedia of Packaging Technology, M. Bakker, Ed., John Wiley & Sons, New York. Williams, D. J. (1971). Polymer Science and Engineering, Prentice-Hall, Englewood Cliffs, New Jersey. Williams, J. C. (1995). "Moisture Absorption, Dimensional Stability, and Density," pp. 324-330 in Nylon Plastics Handbook, M. I. Kohan, Ed., Hanser/Gardner Publication, Inc., Cincinnati, Ohio. Wunderlich, B. and Cormier, C. M. (1967). "Note: Heat of Fusion of Polyethylene," J. Polym. Sci., A-2, 52987-988. Ziegel, K. D., Frensdorff, H. K., and Blair, D. E. (1969). "Measurement of Hydrogen Isotope Transport in Poly (Vinyl Fluoride) Films by Permeation Rate Method," J. Applied Polymer Science, Part A-2(7): 809. Zobel, M. G. R. (1982) "Measurement of Odor Permeability of Polypropylene Packaging Films at Low Odorant Levels," Polymer Testing, 3(2): 133. 119 1131121iiiiIIIIIIIIIIIII-ii 193