{1.3. A}. 55.391) .. ,3... ...., 3 , . , ... ...H.. . 7. . ; I V . 3.1.1425: . (4. .v , ‘f:f .i. ! 5.5.1.1453 _.l... J’titllj’llljllljllllflllllWilli . 9 1843 This is to certify that the thesis entitled THE EFFECT OF SURFACE SULFONATION OF HIGH DENSITY POLYETHYLENE (HDPE) ON THE MECHANICAL PROPERTIES OF HDPE/WOOD FIBER COMPOSITES presented by KOICHI HARAGUCHI has been accepted towards fulfillment of the requirements for L1 IL. W U ' 1 Major professor Date NOVEMBER 18; 1993 0-7539 MS U is an Affirmative Action/Equal Opportunity Institution LIBRARY Michigan State University PLACE IN RETURN BOX to remove this checkout from your record. TO AVOID FINES return on or betore date due. DATE DUE DATE DUE DATE DUE FEB 0219” r ix ‘ ,- ll ’1 , ”M .I as "/ “"11 V DVD 3pm b u u MSU Is An Affirmative Action/Equal Opportunity Institution cum M31“ THE EFFECT OF SURFACE SULFONATION OF HIGH DENSITY POLYETHYLENE (HDPE) ON THE MECHANICAL PROPERT I ES 01" HDPE IWOOD F I BER COMPOS I TES BY Koichi Haraguchi A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE School of Packaging 1993 ABSTRACT THE EFFECT OF SURFACE SULFONATION OF HIGH DENSITY POLYETHYLENE (HDPE) ON THE MECHANICAL PROPERTIES OF HDPE/WOOD FIBER COMPOSITES BY Koichi Haraguchi The ability of surface sulfonation of high density polyethylene (HDPE) resins to enhance interfacial interaction between the HDPE and aspen hardwood fibers, with a concomitant increase in mechanical properties of the resultant composites, was evaluated. Both pelletized and powdered HDPE resin were sulfonated for different lengths of reaction time. The HDPE resins were compounded with 40% weight of the wood fibers in a twin-screw extruder. Maleic anhydride modified polypropylene (MAP?) was also investigated as a coupling agent for the composites. Composite samples were evaluated for tensile, flexural, and impact properties. The effect of a longer reaction time and an increased surface area was shown to result in increased levels of sulfonation. The results showed that sulfonation, at the achieved levels, had little or no effect on enhancing the mechanical properties of the HDPE/wood fiber composites. The inclusion of MAPP resulted in an increased interfacial adhesion between HDPE and wood fibers. The powdered HDPE showed an increased compatibility with wood fibers. To my parents, Yoshiya and Teruko Haraguchi iii ACKNOWLEDGEMENTS Firstly, I would like to express my sincere gratitude to my major professor, Dr. Jack Giacin, for his great guidance, assistance, encouragement, and patience. I would also like to express my appreciation to my guidance committee, Dr. Susan Selke and Dr. Parviz Soroushian, for their useful guidance and support. I would like to thank Mike Rich from the Composite Materials and Structures Center, for his assistance and the use of the extruder, and Rodney Andrew, for his help with sulfonation process. My thanks are extended to Dr. Julian Lee, for his advice on statistical analysis of the test data. I am indebted to the Center for Food and Pharmaceutical Packaging Research, for financial support of this project. I am deeply grateful to the Maruto Sangyo Ltd., for financial support of my study in the School of Packaging. Finally, I would like to express my Special thanks to all my friends, for their friendship, assistance, encouragement, and humor. iv TABLE OF CONTENTS Page LIST OF TABLES .......................................... Vi LIST OF FIGURES ......................................... ix INTRODUCTION ............................................ 1 LITERATURE REVIEW 1. Composite Materials ............................ 7 2. Sulfonation Process ............................ 14 3. Prior Research ................................. 17 MATERIALS AND METHODS 1 0 materials 0 O O O O O O O O O O O O O O O O O O O O O O O O O I O O 0 O O O O O O O O 2 2 2 O MethOdS O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O 0 O O O O O O O 2 4 RESULTS AND DISCUSSION 1. Sulfonation of HDPE ............................ 34 2. Density Measurement of Composites .............. 35 3. Tensile Properties ............................. 36 4. Flexural Properties ............................ 47 5. Impact Resistance .............................. 54 SUMMARY AND CONCLUSIONS ................................. 58 RECOMMENDATION FOR FURTHER RESEARCH ..................... 60 APPENDICES A. Results and Data of DSC ........................ 61 B. Test Data ...................................... 64 C. Statistical Analysis of Data ................... 74 BIBLIOGRAPHY O...0.0...0.00.00.00.00.0.0.0.0000...00.... 101 Table 1. 2. 3. 4. 5. 6. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. LIST OF TABLES Page Composite Composition by % weight ................. 28 Sulfur Concentration of Sulfonated HDPE ........... Results Results Results Results Results Results Results Results Results Density Tensile Modulus Percent of of of of of of of of of Density Measurement of Composites ...... Tensile Strength (MPa) ................. Modulus of Elasticity (MPa) ............ Percent Elongation at Break (%) ...... .. Flexural Yield Strength (MPa) .......... Flexural Modulus (MPa) ................. Impact Strength (J/m) .................. DSC for Pelletized HDPE Resin .......... DSC for Powdered HDPE Resin ............ 34 36 41 43 45 50 52 56 61 61 Measurement Data (gm/cm3) ................ . 64 Strength Data (MPa) OOOOOOOOOOOOOOOOOOOOOOO of ElastiCj-ty Data (MPa) COOOOOOOOCOOOOCOOO Elongation at Break Data (%) .............. Flexural Yield Strength Data (MPa) ................ Flexural MOdulus Data (MPa) OOOOOOOOOOOOOOOOOOOCOOO Impact Strength Data (J/m) ........................ One-Way Analysis of Variance of Density Measurement Values for Composites ................. One-Way Analysis of Variance of Tensile Strength Values for Composites (Lengthwise Fiber Direction) vi 65 66 68 7O 71 72 74 75 21. 22. 23. 24. 25. 26. 27. 28. 29. 300 31. 32. 33. 34. One-Way Analysis of Variance of Tensile Strength Values for Composites (Crosswise Fiber Direction) 0.0.0.0000...OOOOOOOOOOOOOOOOOO0.0 One-Way Analysis of Variance of Modulus of Elasticity Values for Composites (Lengthwise Fiber DireCtion) OOOOOOOOOOOOOOOOOOOOOO0.0.0.0....O One-Way Analysis of Variance of Modulus of Elasticity Values for Composites (Crosswise Fiber Direction) 0......OOOOOOOOOOOOOOOOOOOO000.... One-Way Analysis of Variance of Percent Elongation at Break Values for Composites (Lengthwise Fiber Direction) ...................... One-way Analysis of Variance of Percent Elongation at Break Values for Composites (Crosswise Fiber Direction) ....................... One-way Analysis of Variance of Flexural Yield Strength Values for Composites (Lengthwise Fiber Direction) ........... ..... ...... One-Way Analysis of Variance of Flexural Yield Strength Values for Composites (Crosswise Fiber Direction) ....................... One-Way Analysis of Variance of Flexural Modulus Values for Composites (Lengthwise Fiber Direction) OOOOOOOOOOOOOOOOOOOO0.00.00.00.00. One-Way Analysis of Variance of Flexural Modulus Values for Composites (Crosswise Fiber Direction) OOOOOOOOOOOOO00.000000000000000... One-Way Analysis of Variance of Impact Strength Values for Composites (Lengthwise Fiber Direction) OOOOOOOOOOOOOOOOOOOO0......00.0... One-Way Analysis of Variance of Impact Strength Values for Composites (Crosswise Fiber Direction) 0.0.0.0000...OOOOOOOOOOOOOO0...... One-way Analysis of Variance of Tensile Strength Values for Matrix Materials ....... ...... . One-Way Analysis of Variance of Modulus of Elasticity Values for Matrix Materials . ...... ..... One-way Analysis of Variance of Percent Elongation at Break Values for Matrix Materials vii 76 77 78 79 80 81 82 83 84 85 86 87 88 89 35. 36. 37. 38. One-Way Analysis of Variance of Flexural Yield Strength Values for Matrix Materials ........ One-Way Analysis of Variance of Flexural Modulus Values for Matrix Materials ............... One-Way Analysis of Variance of Impact Strength Values for Matrix Materials .............. One-way Analysis of Variance of Mechanical Property Values for Composites with Lengthwise Fiber Direction vs. Crosswise Fiber Direction ..... viii 9O 91 92 93 LI 81' OF FiGURES Figure Page 1. Reaction of PE Film with 803 ...................... 16 2. Molecular Structure of Cellulose .................. 23 3. Molecular Structure of MAPP ....................... 24 4. Schematic Diagram of Sulfonation System ..... ..... . 25 5. Schematic Cross Section of Extruder ............... 27 6. Tensile Strength .................................. 42 7. Modulus of Elasticity ................. ....... ..... 44 8. Percent Elongation at Break ....................... 46 9. Flexural Yield Strength ... ....... ................. 51 10. Flexural Modulus ........ .......... ..... ....... .... 53 11. Impact Strength ................................... 57 12. DSC Data for Pelletized HDPE Resin ................ 62 13. DSC Data for Powdered HDPE Resin .................. 63 INTRODUCTION Government and industry alike have been seeking methods of disposal, that will deal with the problem of plastics in the solid waste disposal system. In the past, polyethylene terephthalate (PET) was one of the few plastics that was actively sought for recycling. High density polyethylene (HDPE) generates a significantly greater amount of tonnage yearly than PET, therefore both are now being actively sought and recycled. HDPE is readily identified by consumers in the form of plastic milk jugs. In the State of Michigan, for example, over 12,000 tons of plastic milk jugs are discarded each year (Resource Integration Systems Ltd., 1987). HDPE is also used as packaging for household chemicals, bleach, detergent, and cosmetics. Barriers to the recovery of HDPE include contamination and health concerns. Recycled plastics are generally considered unsuitable for direct food content, due to fear of contaminants. An advantage in recovering HDPE is that it is relatively easy to recycle compared with many other plastics. Products manufactured from recycled HDPE include: signs, toys, basecups for soft drink bottles, traffic barrier cones, pipe, and trash cans. Recycled HDPE resin has also been evaluated as a low cost matrix for structural polymer composites. HDPE resin will be evaluated as a matrix material in the present investigation because of its low cost and abundance. HDPE by itself is limited in its use for structural applications, due to its low stiffness and high creep properties. However, if it is reinforced with a stiff and strong filler, these limitations may be overcome. The type of filler used as a reinforcement is very important, since the ultimate properties of the composite are controlled by the properties and quantities of the component materials. The filler should provide maximum improvement of desired physical properties, and be inexpensive and readily available in controlled particle sizes, among other desired requirements. The filler being investigated in this study is aspen hardwood fibers. Advantages of wood fiber include its low density, abundance, high strength-to-weight ratio, and low cost. Previous studies which evaluated the mechanical properties of wood fiber/HDPE composites have shown very little improvement over filled but non-reinforced HDPE. This is not unexpected since wood fibers are polar and hydrophilic, while HDPE is non-polar and hydrophobic. The role of the matrix material or the continuous phase is to bind the fibers and protect them. Although limited bonding may occur as a result of physical entanglement across the interface between the continuous polymer phase and the discontinuous wood fiber phase, the extent of such bonding does not lead to an 3 appreciable enhancement of the mechanical properties of the composites, as compared to non—reinforced HDPE. In the absence of a strong bond between the matrix and fibers, the two may separate. This type of failure is known as de- bonding. With these factors in mind, many fibers and reinforcing agents are pre-treated before they are incorporated into a composite. A common pretreatment uses a coupling agent that acts as a bridge between the filler and matrix, thus creating a stronger bond between the two. Studies have shown that very small additions of a coupling agent are sufficient to promOte good bonding and improve mechanical properties (Keal, 1990 and Childress, 1991). To date, studies have focused on the inclusion of various modifiers with wood fiber/recycled plastic composites, and the effectiveness of the additives to improve the mechanical properties of the composites. The polymer matrices investigated include: (i) high density polyethylene; (ii) polypropylene; and (jJJJ recycled. 'multi-layer polypropylene/adhesive/ ethylene—vinyl alcohol copolymer containers. The multi-component composite was found to have properties superior to those of a composite formed with polypropylene alone (Simpson, 1991). This was attributed to improved fiber adhesion, resulting from the polar functionality of the adhesive and ethylene-vinyl alcohol copolymer components. The inclusion of modifiers to high (lensity polyethylene based composites was found to enhance the mechanical properties of the resultant composites by improving fiber/polymer matrix adhesion (Selke, et al., 1989; Childress, 1991). Two additives which showed promising results were maleic anhydride modified polypropylene, and ionomer modified polyethylene. One of the major parameters governing the mechanical performance of composite materials is the interfacial adhesion between the reinforcing phase and the continuous matrix phase. It is generally accepted that adhesion between the reinforcing phase and the matrix phase in a composite material is dependent on the interfacial chemistry. However, while adhesion and the chemical bonding models of adhesion consider interfacial interactions, the exact nature of the chemistry and physics of adhesion, as they pertain to composite materials, is not fully understood. Modification of the surface energy properties (dispersive and non-dispersive energies) of the HDPE matrix phase offers an opportunity to increase the strength of the adhesion between the reinforcing phase and matrix phase of the composite and enhance the mechanical performance of the composite material. Sulfonation chemistry offers a new approach for chemically and structurally modifying the surface of polymers (Walles, 1989; Walles, 1973; Walles, 1971). Since the sulfonation process attaches the sulfonate groups along the polymer backbone, through a displacement reaction with hydrogen atoms, virtually any polymer except for fluorochloropolymers can be sulfonated. Further, the sulfonation process itself is not surface limited, i.e. the process can be extended under diffusion control below the surface to depths of a micron or more. Thus, modification of not only the surface but the surface region is possible. In principle, this process makes it possible to modify the surface of polymers, independent of their chemical composition, and can be applied to wood fiber/polymer composites resulting in enhanced interfacial adhesion between the fiber and polymer with a concomitant increase in mechanical properties. In this study, surface sulfonation of HDPE will be carried out in order to determine its effect on the mechanical properties of wood fiber/surface sulfonated HDPE composites. Ammonium cation (NH4+) will be used to neutralize the sulfonated HDPE resins, which have been treated at different reaction times, to provide HDPE samples with various levels of sulfonation. Success in this program will lead to the development of a method to modify the surface of polymers, independent of their chemical composition, and can be applied to co-mingled plastics resulting in enhanced compatibility. The primary objectives of this study include: (i) To determine the density and distribution of sulfonate groups on HDPE following surface sulfonation.; (ii) To determine the effect of sulfonate group concentration and depth on the mechanical properties of wood fiber/surface sulfonated HDPE composites. For this study, comparisons will be made between the sulfonated materials and controls formed using non—sulfonated resin with the same percentage of wood fiber. —i—mmuvn ‘ “...-- LITERATURE REVIEW 1. Composite Materials 1.1 Introduction Various types of nmterials such as nwtals, glass, and polymers, each processing specific physical, mechanical and barrier properties, have been utilized by modern industry. A supply of such nmterials is needed for the efficiency, comfort, and convenience of modern human life. Composite materials have also been researched and developed for over fifty years to meet the demands of society. A composite material can be defined as any substance that is made by physically combining two or more existing materials to produce a multiphase system with different properties from the starting materials, but in which the constituents retain their identity (Richardson, 1977). For example, the basic constituents of a composite structure may consist of a polymeric matrix material and fibers. The matrix material is the continuous phase and the fibers are the reinforcing phase of the composite material. The fibers are embedded and surrounded by the matrix resulting in a higher, or enhanced mechanical strength to the composite. The tensile stress applied to the composite material can be transferred through the matrix to the fibers which accounts for the enhanced Imachanical strength of the composite. Thus, the matrix phase 7 typically exhibits lower tensile_ strength than the reinforcing fibers. In addition to the two components, a continuous phase and the reinforcing fibers or discontinuous phase, the fiber-matrix interface is also a very important component of the resultant composite material. The mechanical properties of a composite are significantly affected by the structure and strength of the interface bonding in the composite material (Richardson, 1987). For example, the failure of the composite material may occur, due to the debonding of the fiber—matrix interface, with a corresponding weakening of the interfacial adhesion. In this case, the efficient transfer of stress between the matrix and fibers is not achieved. Surface- treatment of the respective components of the composite is often carried out to reduce the interfacial bonding problem and enhance interfacial adhesion. There are three basic procedures to achieve enhanced interfacial adhesion between the fibers and matrix: (iJ modification of the fibers, (ii) use of a coupling agent, and (iii) modification of the matrix (Krishnan and Narayan, 1992). ‘With respect to the surface modification of the reinforcing fibers, the fibers can be coated with an additive which introduces suitable functional groups, resulting in the fiber surface being more compatible with that of the matrix (Krishnan and Narayan, 1992). A coupling agent, which acts as a bridge to promote adhesion between the fibers and matrix, may be added to the matrix when compounding the fibers. Btu? hydrophobic, non-polar’ matrices such. as polypropylene, or polyethylene, which exhibit incompatibility with hydrophilic polar fibers, modification of the continuous matrix phase can provide a means of introducing polar functionality to the characteristically hydrophobic polymer matrix. The polar nature of the polymers can provide a means of non-covalent interaction with the hydrophilic fiber surface. 1.2 Prediction of Properties The mechanical properties of a composite material depend on the properties of its constituents, their distribution, and physical and chemical interactions (Agarwal and Broutman, 1980). The mechanical properties include the modulus, tensile strength, and impact strength. In order to determine these properties, theoretical estimation is considered an efficient measurement, while experimental measurement is not so due to its cost limitation, time requirements, and difficulty. The modulus of a composite is the easiest property to estimate since it is a bulk property, which depends primarily on the geometry, modulus, particle size distribution, and concentration of the fibers (Bigg, 1987). The modulus of a continuous fiber composite material, EC, can be predicted by the rule of mixtures as (Agarwal and Broutman, 1980): Ec=Efo +53an (1) 10 where: Ef , Em the modulus of the fibers and matrix phase, respectively Vf, Vm = the volume fraction of the fibers and matrix phase, respectively The average tensile stress applied to the continuous fiber composite materials, ob, can also be estimated (Agarwal and Broutman, 1980) by using the simple rule of mixture as: 0c = CIf Vf + (5me (2) 'where: CE: 0% = stress of the fibers and matrix phase, respectively The rule of mixtures indicates that the load on the composite material will be distributed over the fibers and the matrix material according to the ratio of the volume of the fiber and matrix phase and their respective modulus or tensile strength. Moreover, the shared load between the constituents of the composite material will be expressed as: 2:: £ng Pm Emvm (3) where: Pg, P5 = the loads carried by the fibers and matrix, respectively (Agarwal and Broutman, 1980) 11 Equation (3) indicates that a high ratio of the modulus between the constituents will result in the fibers carrying a higher proportion of the load, even with limited volume of fibers (Schliekelmann, 1982). Usually, the loads on the composite materials are directly applied to the matrix and then transferred to the fibers through the fiber ends and also through the cylindrical surface of the fiber near the ends (Agarwal and Broutman, 1980). The continuous fiber composite materials, as described above, are unidirectional composite materials that include similar fiber orientation, which result in the composite having greater tensile strength and a higher modulus in the direction of the fiber axis than in the transverse direction. In contrast, short-fiber (discontinuous fiber) composite materials have an advantageous property in that the stress on the composite is approximately equal in all directions. In addition, composites utilizing short fibers, which can be easily molded by injection or compression molding, are economical and can produce generally isotropic composite materials (Agarwal and Broutman, 1980). The mechanical properties of the short-fiber composite materials were found to be a function of the fiber length. However, for continuous fiber composite materials, where the length of fiber is much greater, stress transfer is not related to the end effects. The length of the fiber which 12 determines the ultimate strength of the fiber, is called the critical length (Holister and Thomas, 1966). The critical length, LC, is obtained from the following equation (Agarwal and Broutman, 1980): £2: “it where: (nu = ultimate strength d = fiber diameter 1& = shear stress The shear stress can be either the shear strength of the matrix or the fiber—matrix interfacial shear strength, whichever is smaller (Schliekelmann, 1982). In order to estimate the average ultimate strength of shorte fiber composite materials, cgu, the following equations can be applied, which include two regions related to the fiber and critical length (Agarwal and Broutman, 1980): o '-Ffl;V '*‘%n V cu d f u n (L < Lo) (5) L 11 = u 1 - —c' f m 0c 0f ( 21.) vi + (0m): V (L > La) (6) 13 where: L = length of fiber qm = ultimate stress of matrix (QQH = stress of matrix at the fiber fracture strain sf When the length of fibers is smaller than the critical length (LC), the maximum fiber stress is less than the average strength of fibers, so that the fibers will not fracture (Agarwal and Broutman, 1980). In this case, therefore, failure of the composite material will occur as a result of failure of the matrix or fiber-matrix interface. When the length of the fiber is greater than the critical length, the fibers can be stressed to their average strength and fracture at the point when the maximum fiber stress reaches the ultimate strength of the fibers (Agarwal and Broutman, 1980). The short—fiber composite materials involve randomly oriented fibers and promote basically an isotropic property. Thus, to predict the modulus of short—fiber composite materials, the longitudinal and transverse modulus in the materials should be considered. The following equation predicts the modulus of the short-fiber composite materials, ErumOm (Agarwal and Broutman, 1980): _ 3 5 Erandom " "EL + ‘ET 8 8 (7) where: EL, ET = longitudinal and transverse modulus 14 There are no viable theoretical relationships between filler characteristics and concentration that can be used to predict the impact strength of reinforced polymers (Bigg, 1987). The impact strength of composite materials depends very strongly on the test procedure as well as other factors such as the rate of impact, shape of the impacting implement, exiStence of microdefects in the vicinity of the impact, fiber orientation, and interfacial adhesion (Bigg et al., 1988). 2. Sulfonation Process 2.1 Introduction Sulfonation is useful technique to provide modification of a polymer surface. To accomplish the sulfonation of polymers such as polyethylene(PE), polypropylene(PP), and polystyrene(PS), the surface of polymers is treated with gaseous 803, fuming sulfuric acid, or $03 in chlorinated hydrocarbons (Ihata, 1988). Virtually any polymer except for fluorochloropolymers can be sulfonated because the sulfonation process attaches the sulfonate groups along the polymer backbone through a displacement reaction with hydrogen atoms. Olsen and Osteraas (1969) proposed from the infrared spectra of surface sulfonated PE films, that the process involved insertion of atomic sulfur into the carbon- hydrogen bonds of the PE surface. This results in the presence of sulfonic acid groups on the polymer surface. Sulfonation of polymer surfaces has been applied to improve their barrier and physical properties. Sulfonated polymers contain a structurally modified surface layer due to the 15 presence of sulfonate groups. The chemical nature of this thin layer results in an enhancement of surface properties of polymers. For example, Walles (1989) indicated an increase in gasoline vapor barrier properties of in-mold sulfonated high density polyethylene (HDPE) automotive gas tanks, with about 20% SO3 in air followed by neutralization with NH3 gas, as compared to untreated HDPE gas tanks. In addition, the exposure of PE to the sulfuric acid atmosphere substantially improved the hardness, surface tension, and conductivity of the thin sulfonated surface (Fonseca et al., 1985). Surface sulfonation of polymers is usually carried out to enhance the hydrophilic (e.g. ion-exchange resin from styrene—divinylbenzene copolymers) or water soluble nature of the matrix (e.g. sulfonated PS) (Planche et al., 1988). The sulfonic acid groups attached to the polymer backbone account for the polar or hydrophilic nature of the surface sulfonated polymers. Kinetic studies predicted that the sulfonation process is dependent on the concentration of the 803 species and time of exposure of the polymer to the 803 gas (Walles, 1989). The thickness of the thin surface layer that includes sulfonate groups can be extended under diffusion control below the matrix surface to depths of a micron or more. Thus the sulfonation process itself is not surface limited, and it is possible to modify not only the surface but the surface region of the polymers. The surface of polymer resins that are formed as pellets or powders may also be treated by the 16 sulfonation process. 2.2 Reaction of pglyethylene with $03 The behavior of SO3 in chemical reactions shows that the sulfur atom is strongly electron-deficient while the oxygen agents are electron-rich (Gilbert, 1965). The nature of SO3 leads to its activity as a sulfonating agent. Ihata (1988) described the reaction of gaseous $03 with PE film, which was evaluated by spectrophotometric analyses including infrared (IR), ultraviolet (UV-VIS), and resonance Raman spectroscopy. The reaction which yields sulfonated PE is initiated by the abstraction of a hydrogen atom of the PE backbone by 803, as shown in Figure 1. This reaction then proceeds by further reactions which include: (i) 803 can react with a carbon atom of the PE backbone resulting in the sulfonic acid group being covalently bound to the PE surface; (ii) the sulfonated membrane can undergo elimination of two hydrogen atoms, resulting in an unsaturated bond. $03 -CH2-CH2-CH2- —> -CH2-CH2-¢H- ——> -CH2-CH2-(|:H- (8) SO3H 80311 —> -CH2-CH=CH- (9) -HzSO3 Figure 1. Reaction of PE film with so3 (Ihata, 1988) 17 The sulfonic acid groups are then easily neutralized with NH3. The neutralization results in the presence of -C-SO3'NHf'1 Heating Heating Heating zone 1 Zone 2 zone 3 Figure 5. Schematic Cross Section of Extruder Polymer resin was placed in the automatic feeder and fed into zone 1 through the hopper. For fabricating the composites which included the addition of MAPP, the HDPE was mixed with MAPP and then placed in the feeder. When the melted polymeric material reached zone 2 of the extruder barrel, wood fibers were carefully added by hand at a constant feeding rate. Before each extrusion process, to achieve an accurate mixing ratio of polymer to wood fibers by weight, the specific feed rate of the automatic feeder was first determined. Resin samples exiting through the automatic feeder during a two minutes period were collected. This procedure was repeated to give five replicate values which were then weighed to provide the specific feed rate, as expressed in gm/min. The range of the specific feed rate 28 values of the automatic feeder was 4.1 to 6.7 gm/min. The feed rate for the fibers (gm/min) was then calculated, with regard to the % weight of wood fibers (40%) for all composites achieved. The range of the feed rate values for fibers was 2.7 to 4.5 gm/min. The compounded materials exited through the die were cut into bars of approximately 10 cm in length. The weight of each sample was approximately 24 grams. A total of eight runs of the extrusion process was carried out to obtain a series of HDPE/wood fiber composites. Table 1 summarizes the composition by % weight of the respective composites fabricated. Table 1. Composite Composition by % weight Composite No. Composition (% weight) C1 60% pelletized HDPE/40% wood fiber C2 60% sulf.(2min)pelletized HDPE/40% wood fiber C3 60% sulf.(4min)pelletized HDPE/40% wood fiber C4 60% powdered HDPE/40% wood fiber C5 60% sulf.(3min)powdered HDPE/40% wood fiber C6 55% pelletized HDPE/5% MAPP/40% wood fiber C7 55% sulf.(2min)pelletized HDPE/5% MAPP/40% wood fiber C8 55% sulf.(4min)pelletized HDPE/5% MAPP/40% wood fiber 29 2.3 Compression Molding The compounded materials were compression molded by using a Carver Model M 25 ton laboratory press compression molding machine. To form a sheet, three samples of the compounded materials were placed into a frame that was covered by metal plates. The specific frame size employed was dependent on the type of test to be performed on the fabricated composite sheet. The specific frame dimensions were as follows: 15 x 15 x 0.25 cm for the tensile test; and 12.7 x 12.7 x 0.3175 cm for the flexural and impact tests. A.pflastic film (Polyethylene terephthalate)was placed between the frame and metal plates to reduce any sticking to the surfaces of the frame and heated metal plates. The compounded material was heated at a temperature of 150°C for 10 minutes under a pressure of 30,000 psi, and then cooled down to a temperature of 609C by circulating cold water, for approximately 7 minutes, through the press. 2.4 Tensile Test Tensile strength at break, percent elongation at break, and modulus of elasticity were determined by an Instron Universal Tensile Tester (United Model SFM test system, United Calibration Corporation, Huntington Beach, California) at room.conditions (23WC, 50% RH). The test procedure was based on ASTM Standard D638—87b, Standard Test Method for Tensile Properties of Plastics (ASTM, 1988). Dumbbell-shaped Type I specimens were produced by using a Tensilkut Model 10-13 -—-“-. .w-_ ... _. .7 30 specimen cutter (Tensilkut Engineering, Danbury, Connecticut). The dimensions of the specimens were: total length, 150 mm; width, 20 mm; thickness, 2.5 mm; width of narrow section, 10 mm. The test conditions of the Instron. Universal Tester system were: full scale load, 1000 lbs; crosshead speed, 0.21 in./min. for the composites and 2 in/min for pure polymers, respectively; grip separation, 3.5 in. The respective values of the tensile properties were automatically calculated by a computer system using the following equations: Tensile strength at break, 0 o = ll A0 (8) where: W = maximum load Am = original cross-sectional area Percent elongation at break, %El %E1 = (L ' I”) x 100 Lo 1 = s x 100 (9) ‘where: L = extended grip separation at break In = original grip separation e = strain 31 Modulus of elasticity E o E=._£1. 8d (10) where: cq_= difference in stress corresponding to any segment of section on initial straight line portion of stress-strain curve 8a difference in strain corresponding to any segment of section on initial straight line portion of stress-strain curve 2.5 Flexural Test Flexural yield strength and flexural modulus were determined by an Instron Universal Tensile Tester (United Model SFM test system, United Calibration Corporation, California) at room conditions (23W:, 50% RH). The test procedure was based on ASTM Standard D790-86, Standard Test Method for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials (ASTM, 1986). Method I, which sets a loading nose and two supports to the specimen, was used. For the test specimens, the molded sheets were cut into samples with a length of 127 mm and a width of 12.7 mm. The following parameters were set on the Instron Universal Tester system: load cell, 20 or 1000 lbs; crosshead speed, 0.08 in/min; support span, 2.0 in. The respective values of the properties were automatically calculated by the computer system, using the following 32 equations: Flexural yield strength, 8 s= 3PL 2bd2 (11) where: P = load at a point, which the load does not increase with an increase in deflection L = support span b = width of beam tested d = depth of beam tested Flexural modulus, E5 E: L3m B — 4bd3 (12) where: m = slope of the tangent to the initial straight line portion of the load-deflection curve 2.6 Impact Test Izod impact strength was determined by a TMI 43-1 Izod Impact Tester (Testing Machines, Inc., Amityville, New York) at room conditions (23%:, 50% RH). The test procedure was based on ASTM standard D256-87, Standard Test Method for Impact Resistance of Plastics and Electrical Insulating Materials (ASTM, 1988). The molded sheets were cut into test specimens ‘with.a.length of 63.5 mm and a width of 10 mm. The specimens were then notched using a TMI Notching Cutter, where the angle of the notch was 45 degrees with a radius of curvature 33 at the apex of 0.25 mm. The pendulum load used was 5 ft-lbs. The impact strength was automatically calculated using the system. of the tester, which was calibrated by the manufacture. 2.7 Density Measurement Density of specimens was determined for all composites. The dimensions, which included length, width, and thickness, of un-notched specimens that were prepared for the impact test were measured using a micrometer to get the volume of the respective specimens. The test specimens were also accurately weighed, and the weight was divided by the volume, to obtain density values, as expressed in gm/cm3. 2.8 Statistical Analysis SPSS/PC+ statistical program (version 4.0, Michigan State University, 1990) was used to perform statistical analysis of test data for tensile strength, modulus of elasticity, percent elongation at break, flexural yield strength, flexural modulus, impact strength, and density measurement. The following statistical analysis procedures were performed: (i) a one way analysis of variance of mechanical properties and density measurement values for composites; (ii) a one way analysis of variance of.nechanical properties values for matrix materials; and (iii) a one way analysis of variance of mechanical property values for composites with lengthwise fiber direction vs. crosswise fiber direction. RESULTS AND DISCUSSION 1. Sulfonation of HDPE Table 2 summarizes the results of elemental analysis performed on both sulfonated pelletized and powdered HDPE. As shown, very low levels of sulfonation were achieved for the respective HDPE samples, under the reaction conditions employed, which were ambient temperature and 1% $03 (V/V). Table 2. Sulfur Concentration of Sulfonated HDPE Reaction Sulfur Concentration Type of HDPE Time (min . ) (%Su1 fur (wt/wt) ) Pelletized 2 0.0012 Pelletized 4 0.0034 Powdered 3 0.05 The presence of the low concentration levels of sulfur in the HDPE resins following reaction with 803, indicates a lack of reactivity of the surface region of the polymer resins to the sulfonation process. In the sulfonation process, 503 reacts with a carbon atom on the HDPE backbone and is neutralized with NH3 gas. This results in the sulfonic acid groups being 34 35 covalently bonded to the HDPE surface. Comparing the two different reaction times with gaseous $03 in the sulfonation process, the 4 min. sulfonated pelletized HDPE exhibited approximateLy a three times higher sulfur concentration than the 2 min. sulfonated pelletized HDPE. These findings confirmed that a longer reaction time resulted in the sulfonated HDPE having a higher sulfur content. In comparing sulfonation of the pelletized and powdered HDPE resins, the 3 min. powdered HDPE had approximately fifteen times higher sulfur content than the 4 min. sulfonated pelletized HDPE, despite the shorter reaction time. The greater surface area of the powdered HDPE resin, as compared to the pelletized resin, could account for the enhanced level of sulfonation achieved. The effect of a longer reaction time and an increased surface area has been shown to result in increased levels of sulfonation. However, the extent of sulfonation achieved was quite low and, as described in the following sections, did not modify the dispersive and polar characteristics of the polymer to a level which would result in enhanced interfacial interaction between the HDPE and wood fibers, with a concomitant increase in mechanical properties. 2. Density Measurement of Composites Ten replicate specimens of the respective composites were measured to determine their density values. Table 3 lists 36 the mean density values for each composite, in units of gm/cm3. There were no significant differences between the means of the respective composites, based on statistical analysis, as shown in Table 19, Appendix C. This result supports the achievement of uniformly compounded experimental materials for all composites. Table 3. Results of Density Measurement of Composites Density Composite (gm/cm3 ) No. Composite (% weight) Mean SD C1. 60% Pel.HDPE/40% Fiber 1.06 0.01 C2. 60% Sulf.(2min)Pel.HDPE/40% Fiber 1.06 0.02 C3. 60% Sulf.(4min)Pel.HDPE/40% Fiber 1.05 0.02 C4. 60% Powd.HDPE/40% Fiber 1.08 0.01 C5. 60% Sulf.(3min)Powd.HDPE/40% Fiber 1.08 0.02 C6. 55% Pel.HDPE/5% MAPP/40% Fiber 1.06 0.03 C7. 55% Sulf.(2min)Pel.HDPE/5% MAPP/40% Fiber 1.07 0.01 C8. 55% Sulf.(4min)Pel.HDPE/5% MAPP/40% Fiber 1.06 0.04 3. Tensile Properties The mean of 10 to 14 replicate samples of the respective composite materials was determined for tensile properties, which included both the lengthwise and crosswise fiber 37 directions. The mean of 10 samples of the respective polymer matrices was also evaluated. The results of tensile property tests are summarized in Tables 4 to 6, where the respective tensile strength, modulus of elasticity, and percent elongation values are presented. The effect of sulfonation as well as the effect of the coupling agent (MAPP) on the mechanical properties of the respective composites is shown by the histograms presented in Figures 6 to 8. A one-way analysis of variance of tensile properties values was performed for the respective composites and matrix materials, to determine any significant difference between the means, at an alpha level of 0.05. The results of the statistical analysis are shown in Tables 20 to 25, 32 to 34, and 38, Appendix C. 3.1 Influence of fiber direction For the composites tested, with the exception of the modulus of elasticity of the composites, C1, C6, C7, and C8, the means of the tensile properties in the lengthwise fiber direction showed higher values than those in the crosswise fiber direction. This may be due to orientation of fibers, where the loads on the composite were applied to the polymer and transferred to the fibers through the fiber ends more effectively in the direction of the fiber axis than in the transverse direction. However, theoretically, discontinuous fiber composites, as tested in this study, have the property that the stress on the composite is approximately equal in all directions (See literature review, 1.2). In the present study, the observed decrease in the tensile properties in the 38 crosswise fiber direction may be due to the interfacial failure between the extruded bar during the process of compression molding, where three pieces of extruded bar were molded together to form a sheet for specimen sampling. 342* Influence of Sulfonated HDPE In comparison of tensile properties of the non-sulfonated HDPE composite and sulfonated HDPE composite, the following pairs were evaluated: (i) C1 to C2 and C3; (ii) C4 to C5; and (iii) C6 to C7 and C8, respectively. For the respective pairs compared, the following significant differences between tensile properties were observed, which were based on statistical analysis: (i) an increase in tensile strength of C3 in crosswise fiber direction; (ii) a decrease in tensile strength of C3 in lengthwise fiber direction and of C5, C7, C8 in crosswise fiber direction; (iii) an increase in modulus of elasticity of C3 in lengthwise fiber direction and of C8 in both lengthwise and crosswise fiber direction; (iv) a decrease in modulus of elasticity of C2 in crosswise fiber direction; (v) an increase in percent elongation at break of C2 in crosswise direction; and (vi) a decrease in percent elongation at break of C3 in lengthwise fiber direction. The differences observed seemed to be of little or no practical value and not enough to find utility in the effect of sulfonation on the resultant composites. Thus, sulfonation at the achieved levels had little or no effect on enhancing the tensile properties of the respective composite. These results can be attributed to the low levels of sulfonation achieved and the resultant low level of enhanced interfacial 39 interaction between the HDPE and wood fibers. 3.3 Influence of a coupling agent The composite fabricated with MAPP as a coupling agent, C6, showed a statistically significant increase in tensile strength and modulus of elasticity, as compared to the untreated composite, C1. This is shown graphically in Figures 6 and 7. A similar finding had been reported earlier by Childress (1991). A coupling agent acts as a bridge to promote interfacial adhesion between the fibers and matrix (Richardson, 1977). For the composite, C6, the stress applied on the composite was more effectively transmitted through the matrix to fibers, resulting in the higher tensile strength and modulus of elasticity. In contrast, the composite, C6, had a significant decrease in the percent elongation at break, as compared to the composite, C1 (See Figure 7). Miles and Rostami (1992) proposed that an increase in interfacial bonding resulted in a corresponding increase in the tensile strength, but a decrease in the elongation at break, due to the reduction of the toughness, for glass-filled polypropylene. This finding suggests that the inclusion of MAPP resulted in the composite having lower flexibility and toughness, as well as an increase in its brittleness. Conversely, the composite had a higher stiffness, as estimated by the tensile strength and modulus of elasticity . 3.4 Influence of Powdered HDPE The composite fabricated with powdered HDPE, C4, showed a 40 statistically significant increase in the tensile strength and modulus of elasticity, as compared to that with pelletized HDPE, C1, as shown in Figures 6 and 7, respectively. These findings suggest that powdered HDPE may have a higher degree of compatibility with wood fibers, than pelletized HDPE resin. This can account for the observed enhanced tensile strength and modulus of elasticity values for the powdered HDPE based composites. The effective compatibility might be achieved in the compounding process of the wood fibers and powdered HDPE, where the fibers were uniformly dispersed throughout the matrix. The powdered HDPE seemed to have a more constant filling ability into the fibers than the pelletized HDPE resin, due to its smaller volume per piece. It should be noted that the increased tensile properties of the resultant composites may also be attributed in part to differences between pelletized and powdered HDPE in terms of the molecular weight and molecular weight distribution of the respective matrix materials. However, there were no statistically significant differences of tensile strength and modulus of elasticity values between the pelletized HDPE, P1, and powdered HDPE, P4. This finding suggests that the molecular weight and molecular weight distribution of the powdered and pelletized HDPE resin samples were similar. 41 Table 4 . Results of Tensile Strength (MPa) Comp. Fiber Ho. Composite Direction Mean SD C1. Pel.HDPE/Fiber Lengthwise 23.7 2.1 Crosswise 10.6 0.2 C2. Sulf.(2min)Pel.HDPE/Fiber Lengthwise 23.1 1.2 Crosswise 11.2 0.2 C3. Sulf.(4min)Pel.HDPE/Fiber Lengthwise 20.6 0.2 Crosswise 11.5 0.4 C4. Powd.HDPE/Fiber Lengthwise 27.1 0.1 Crosswise 17.4 0.2 C5. Sulf.(3min)Powd.HDPE/Fiber Lengthwise 26.1 1.8 Crosswise 15.2 0.1 C6. Pel.HDPE/MAPP/Fiber Lengthwise 27.3 1.4 Crosswise 21.4 0.2 C7. Sulf.(2min)Pe1.HDPE/MAPP/Fiber Lengthwise 24.1 1.1 Crosswise 20.6 1.3 C8. Sulf.(4min)Pel.HDPE/MAPP/Fiber Lengthwise 28.8 0.6 Crosswise 20.4 0.8 Pl. Pel.HDPE 30.7 1.6 P2. Sulf.(2min)Pel.HDPE 31.1 0.2 P3. Sulf.(4min)Pel.HDPE 31.0 0.7 P4. Sulf.(3min)Powd.HDPE 30.2 0.9 Tensile strength (MPa) 35 42 Figure 6. Tensile Strength 30" I Lengthwise Crosswise c1 c2 c3 c4 c5 cs c7 ca p1 pz P3 Composite c1. Pel.HDPE/Fiber p1. Pel.HDPE c2. Sulf.(2min)Pe1.HDPE/Fiber 22. Sulf.(2min)Pel.HDPE c3. Sulf.(4min)Pel.HDPE/Fiber 23. Sulf.(4mdn)Pe1.HDPE c4. Powd. HDPE/Fiber p4. Sulf.(3min)Powd.HDPE c5. Sulf.(3min)Powd.HDPE/Fiber cs. Pel.HDPE/HAPP/Fiber c7. Sulf.(2min)Pel.HDPE/MAPP/Piber ca. Sulf.(4min)Pel.HDPE/MAPP/Fiber 43 Table 5. Results of Modulus of Elasticity (MPa) Comp. Fiber Ho. Composite Direction Mean SD Cl. Pel.HDPE/Fiber Lengthwise 1730 91 Crosswise 1934 38 C2. Sulf.(2min)Pel.HDPE/Fiber Lengthwise 1518 210 Crosswise 243 91 C3. Sulf.(4min)Pel.HDPE/Fiber Lengthwise 2150 53 Crosswise 1905 67 C4. Powd.HDPE/Fiber Lengthwise 2544 36 Crosswise 2194 5 C5. Sulf.(3min)Powd.HDPE/Fiber Lengthwise 2555 69 Crosswise 2165 58 C6. Pel.HDPE/MAPP/Fiber Lengthwise 2004 436 Crosswise 2112 453 C7. Sulf.(2min)Pel.HDPE/MAPP/Fiber Lengthwise 2072 212 Crosswise 2280 87 C8. Sulf.(4min)Pel.HDPE/MAPP/Fiber Lengthwise 2328 14 Crosswise 2378 33 P1. Pel.HDPE 890 148 P2. Sulf.(2min)Pel.HDPE 1342 36 P3. Sulf.(4min)Pel.HDPE 1235 66 P4. Sulf.(3min)Powd.HDPE 807 265 44 Figure 7. Modulus of Elasticity 3000 2500 — I Lengthwise Crosswise 2000 '- ...: U‘ 0 O H O O O Modulus of elasticity (MPa) C2 C3 C4 C5 C6 C7 C8 P1 P2 P3 Composite c1. Pel.HDPE/Fiber p1. Pel.HDPE c2. Sulf.(2min)Pel.HDPE/Fiber pz. Sulf.(2min)Pel.HDPE c3. Sulf.(4min)Pe1.HDPE/Fiber p3. Sulf.(4min)Pel.HDPE c4. Powd. HDPE/Fiber p4. Sulf.(3min)Powd.HDPE C5 . Sulf. (3min)Powd.HDPE/Fiber C6 . Pel . HDPE/MAPP/Fiber C7. Sulf. (2min)Pel.HDPE/HAPP/Fiber C8. Sulf. (4min)Pe1.BDPE/MAPP/Fiber 45 Table 6. Results of Percent Elongation at Break (%) Comp. Fiber Mo. Composite Direction Mean SD C1. Pel.HDPE/Fiber Lengthwise 3.2 0.4 Crosswise 1.5 0.04 C2. Sulf.(2min)Pel.HDPE/Fiber Lengthwise 3.4 0.3 Crosswise 2.5 0.1 C3. Sulf.(4min)Pel.HDPE/Fiber Lengthwise 2.3 0.3 Crosswise 1.4 0.3 C4. Powd.HDPE/Fiber Lengthwise 2.1 0.3 Crosswise 1.2 0.1 C5. Sulf.(3min)Powd.HDPE/Fiber Lengthwise 1.8 0.3 Crosswise 1.1 0.1 C6. Pel.HDPE/MAPP/Fiber Lengthwise 2.4 0.5 Crosswise 2.0 0.5 C7. Sulf.(2min)Pel.HDPE/MAPP/Fiber Lengthwise 2.2 0.3 Crosswise 1.7 0.2 C8. Sulf.(4min)Pel.HDPE/MAPP/Fiber Lengthwise 2.4 0.01 Crosswise 1.7 0.2 P1. Pel.HDPE 84.4 75.5 P2. Sulf.(2min)Pel.HDPE 185.3 92.9 P3. Sulf.(4min)Pel.HDPE 115.1 77.8 P4. Sulf.(3min)Powd.HDPE 39.2 11.6 Percent elongation at break (%) Figure 8. 46 Percent Elongation at Break Cl I Lengthwise Crosswise C2 C3 C4 C5 C6 C7 Composite C1 . Pel . HDPE/Fiber P1 . Pel . HDPE C2 . Sulf . (2min)Pel.HDPE/Fiber P2 . Sulf. (2min)Pe1.HDPE c3. Sulf.(4min)Pel.HDPE/Fiber 93. Sulf.(4min)Pe1.HDPE C4 . Pawd. HDPE/Fiber P4 . Sulf . (3min)Powd.HDPE C5 . Sulf. (3min)Powd.HDPE/Fiber C6. C7. C8. Pel . HDPE/MAPP/Fiber Sulf. (2min)Pel.HDPE/MAPP/Fiber Sulf . (4min)Pel .HDPE/MAPP/Fiber 47 4. Flexural Properties The mean of 5 replicate samples of the respective composites, which included the lengthwise and crosswise fiber directions, as well as the mean of the homopolymer matrix was determined for flexural yield strength and flexural modulus. The results of the flexural tests are summarized in Tables 7 and 8, and presented graphically in Figures 9 and 10, respectively. A one-way analysis of variance of flexural properties values was performed for the respective composites and matrix materials, to determine any significant difference between the means, at an alpha level of 0.05. The results of the statistical analysis are shown in Tables 26 to 29, 35, 36, and 38, Appendix C. 4.1 Influence of fiber direction For flexural properties of all composites except for the flexural modulus of composite, C7, the means of values in the lengthwise fiber direction exhibited higher flexural properties than those in the crosswise fiber direction. This result might also be related to the interfacial failure of mixed extruded bars in the process of the compression molding, as described in the previous section (3.1). 4.2 Influence of Sulfonated HDPE In comparison of flexural yield strength and flexural modulus, between the non-sulfonated HDPE composites and the sulfonated HDPE composite structures, the following pairs were used: (i) C1 to C2 and C3; (ii) C4 to C5; and (iii) C6 to C7 and C8. For the respective pairs compared, the 48 following significant differences of flexural yield strength were observed, which were based on statistical analysis: an increase in flexural yield strength of C7 in cross fiber direction; and a decrease in flexural strength of C2, C3, and C5 in crosswise fiber direction. In addition, no statistically significant differences of flexural modulus were exhibited, for the respective sample pairs compared. Thus, sulfonation of the HDPE resins had little or no effect on the flexural properties of the resultant composites. As previous discussed, these findings may be attributed to the low levels of sulfonation achieved, which resulted in little change in the dispersive and polar characteristics of the polymer and therefore little increase in interfacial interaction between the polymer and wood fibers. 4.3 Influence of Coupling Agent Both flexural yield strength and flexural modulus were determined to evaluate the stiffness of the composites tested, which is a measure of the ability of the composite to resist bending forces without failure. The stiffness is very dependent on the interfacial bonding between fiber and polymer, as a higher bonding network will increase the stiffness of the sample. As shown in Figure 9, the addition of MAPP as a coupling agent significantly improved the flexural yield strength of the composite, C6, as compared to the untreated HDPE composite, C1, for both the lengthwise and crosswise fiber direction. The differences were confirmed by statistical analysis. These findings show the effect of the coupling agent on increasing the interfacial bonding between 49 wood fiber and HDPE. For flexural modulus, there were no statistically significant differences between the respective composites. 4.4 Influence of Powdered HDPE As shown in Figure 9, the composite prepared with powdered HDPE, C4, exhibited a significant increase in the flexural yield strength, as compared. to that fabricated. with pelletized HDPE, C1, for the lengthwise direction. As comparison between the flexural strength of the respective matrix materials used to fabricate the composites, pelletized HDPE, P1, and 3 min. sulfonated powdered HDPE, P4, were evaluated. This result illustrates the effect of powdering of the polymer resin on the flexural yield strength of the resultant composites, and may be attributed to the effective compatibility between powdered HDPE and wood fibers. It should be noted that the increased flexural yield strength of the resultant composites may also be attributed in part to differences between pelletized and powdered HDPE, in terms of the molecular weight and molecular weight distribution of the respective matrix materials. However, the observed flexural strength values of pelletized HDPE, P1, and powdered HDPE, P4, were not found to be statistically different. This finding suggests that there was no difference of molecular weight and. molecular' weight distribution between the pelletized and powdered HDPE resins. Based on statistical analysis, a significant increase in the flexural modulus of composite, C4, in the crosswise direction, was exhibited, as compared to composite, C1. 50 Table 7. Results of Flexural Yield Strength (MPa) Comp. Fiber No. Composite Direction Mean SD C1. Pel.HDPE/Fiber Lengthwise 38.3 3.9 Crosswise 29.2 1.5 C2. Sulf.(2min)Pe1.HDPE/Fiber Lengthwise 39.2 5.3 Crosswise 23.9 1.1 C3. Sulf.(4min)Pel.HDPE/Fiber Lengthwise 37.3 7.3 Crosswise 22.7 0.9 C4. Powd.HDPE/Fiber Lengthwise 54.6 5.1 Crosswise 30.0 1.5 C5. Sulf.(3min)Powd.HDPE/Fiber Lengthwise 50.2 2.4 Crosswise 27.4 0.6 C6. Pel.HDPE/MAPP/Fiber Lengthwise 48.4 4.4 Crosswise 37.7 1.6 C7. Sulf.(2min)Pel.HDPE/MAPP/Fiber Lengthwise 50.0 1.0 Crosswise 41.3 2.9 C8. Sulf.(4min)Pel.HDPE/MAPP/Fiber Lengthwise 57.0 5.8 Crosswise 36.8 1.6 P1. Pel.HDPE 27.2 0.7 P2. Sulf.(2mdn)Pel.HDPE 30.0 0.3 P3. Sulf.(4min)Pel.HDPE 29.0 1.2 P4. Sulf.(3min)Powd.HDPE 27.3 1.0 Flexural yield strength (MPa) Figure 9. 51 Flexural Yield Strength 60 50- I Lengthwise Ea Crosswise c2 c3 c4 c5 C6 c7 ca p1 92 P3 Composite c1. Pel.HDPE/Fiber p1. Pel.HDPE c2. Sulf.(2min)Pel.HDPE/Fiber pz. Sulf.(Zmin)Pe1.HDPE c3. Sulf.(4min)Pe1.HDPE/Fiber P3. Sulf.(4min)Pel.HDPE c4. Powd. HDPE/Fiber 94. Sulf.(3min)Powd.HDPE c5. Sulf.(3min)Powd.EDPE/Fiber cs. Pel.HDPE/MAPP/Fiber c7. Sulf.(2min)Pel.HDPE/MAPP/Fiber cs. Sulf.(4min)Pel.HDPE/MAPP/Fiber 52 Table 8. Results of Flexural Modulus (MPa) Comp. Fiber Ho. Composite Direction Mean SD C1. Pel.HDPE/Fiber Lengthwise 10323 2134 Crosswise 8076 1977 C2. Sulf.(2min)Pel.HDPE/Fiber Lengthwise 9599 2630 Crosswise 5339 505 C3. Sulf.(4min)Pel.HDPE/Fiber Lengthwise 13190 2724 Crosswise 7621 1438 C4. Powd.HDPE/Fiber Lengthwise 16235 2308 Crosswise 14060 2890 C5. Sulf.(3min)Powd.HDPE/Fiber Lengthwise 14801 4507 Crosswise 9975 1289 C6. Pel.HDPE/MAPP/Fiber Lengthwise 13871 2760 Crosswise 10786 3120 C7. Sulf.(2min)Pel.HDPE/MAPP/Fiber Lengthwise 12713 2424 Crosswise 12793 2725 C8. Sulf.(4min)Pel.HDPE/MAPP/Fiber Lengthwise 14801 6113 Crosswise 13361 3021 P1. Pel.HDPE 3814 475 P2. Sulf.(2min)Pe1.HDPE 3693 425 P3. Sulf.(4min)Pel.HDPE 3609 460 P4. Sulf.(3min)Powd.HDPE 5889 1706 53 Figure 10. Flexural Modulus 18000 16000 -‘ 14000 — 12000 — 10000 8000 6000 Flexural modulus (MPa) 4000 2000 I Lengthwise Crosswise c2 c3 c4 c5 C6 c7 cs P1 P2 P3 P4 Composite c1. Pel.HDPE/Fiber P1. Pel.HDPE c2. Sulf.(2min)Pe1.EDPE/Fiber P2. Sulf.(Zmin)Pe1.HDPE c3. Sulf.(4min)Pel.HDPE/Fiber P3. Sulf.(4min)Pel.HDPE c4. Powd. HDPE/Fiber P4. Sulf.(3min)Powd.HDPE c5. Sulf.(3min)Powd.HDPE/Fiber cs. Pel.HDPE/MAPP/Fiber C7 . Sulf. (2min)Pe1.HDPE/MAPP/Fiber ca. Sulf.(4min)Pe1.HDPE/MAPP/Fiber 54 5. Impact Resistance The means of 9 to 10 replicate samples of the respective composites, which included the lengthwise and crosswise fiber directions, were obtained to compare the impact strength of the various structures. The» impact strength. of 'the sulfonated and non—sulfonated HDPE resin samples was also determined for comparison. The results of the impact tests are summarized in Table 9, and presented graphically in Figure 11. A one-way analysis of variance of impact strength values was performed for the respective composites and matrix materials, to determine any significant difference between the means, at an alpha level of 0.05. The results of the statistical analysis are summarized in Tables 30, 31, 37, and 38, Appendix C. 5.1 Influence of fiber direction For all composites evaluated, the means of the impact strength in the lengthwise and crosswise fiber directions showed similar values and were not found to be statistically different with respect to fiber direction. 5:27 Influencefof Sulfonated HDPE In comparison of the impact strength of the untreated HDPE composite and sulfonated HDPE composite structures, the following pairs were evaluated: (i) C1 to C2 and C3; (ii) C4 to C5; and (iii) C6 to C7 and C8, respectively. Based on statistical analysis, no significant differences within treatments were observed. These findings are attributed to the low levels of sulfonation achieved (See section 1). 55 5.3 Influence of Coupling Agent A statistically significant decrease in the impact strength for the composite fabricated with MAPP as a coupling agent, C6, was exhibited, when compared to the untreated HDPE composite, C1, as shown in Figure 11. Further, the composite, C6, was found to have lower impact strength than the powdered HDPE composite, C4. Good interfacial adhesion between the filler and polymer improves the tensile strength of the resultant composites. However, it also increases the tendency for brittle failure and makes the composite more notch sensitive (Richardson, 1977). Therefore, these results confirmed that the inclusion of MAPP promoted a higher degree of interfacial bonding between fibers and HDPE. In other words, inclusion of a coupling agent resulted in the composite having less flexibility and toughness, due to the brittleness. 5.4 Influence of Powdered HDPE As shown in Figure 11, the powdered HDPE, P4, exhibited higher impact strength than the pelletized HDPE, P1. Further, the powdered HDPE composite, C4, exhibited a significant decrease in impact strength, as compared to the pelletized HDPE composite, C1. This was confirmed by statistical analysis. These findings indicate that the composite, C4, experienced a reduction in toughness. This may be due to an increased compatibility of the fibers within the polymer matrix, resulting in a more rigid and brittle composite structure. 56 Table 9. Results of Impact Strength (J/m) Comp. Fiber Mo. Composite Direction Mean SD C1. Pel.HDPE/Fiber Lengthwise 52.6 6.7 Crosswise 47.7 5.5 C2. Sulf.(2min)Pel.HDPE/Fiber Lengthwise 54.2 7.9 Crosswise 51.4 7.0 C3. Sulf.(4min)Pel.HDPE/Fiber Lengthwise 55.9 5.0 Crosswise 52.3 7.9 C4. Powd.HDPE/Fiber Lengthwise 44.0 4.6 Crosswise 36.9 2.7 C5. Sulf.(3min)Powd.HDPE/Fiber Lengthwise 42.9 3.7 Crosswise 39.7 5.6 C6. Pel.HDPE/MAPP/Fiber Lengthwise 33.4 4.4 Crosswise 31.1 6.0 C7. Sulf.(2min)Pel.HDPE/MAPP/Fiber Lengthwise 33.0 4.0 Crosswise 32.4 6.1 C8. Sulf.(4min)Pel.HDPE/MAPP/fiber Lengthwise 32.4 2.3 Crosswise 30.7 1.3 P1. Pel.HDPE 100.6 4.8 P2. Sulf.(2min)Pel.HDPE 104.8 10.9 P3. Sulf.(4min)Pel.HDPE 110.6 15.2 P4. Sulf.(3min)Powd.HDPE 128.6 11.0 Impact strength (J/m) 57 Figure 11. Impact Strength 125— 100 - I Lengthwise Crosswise c1 c2 c3 c4 c5 cs c7 ca Composite c1. Pel.HDPE/Fiber P1. Pel.HDPE c2. Sulf.(2min)Pe1.EDPE/Fiber P2. Sulf.(2min)Pel.HDPE c3. Sulf.(4min)Pel.HDPE/Fiber P3. Sulf.(4min)Pel.HDPE c4. Powd. HDPE/Fiber P4. Sulf.(3min)Powd.HDPE c5. Sulf.(3min)Powd.HDPE/Fiber cs. Pel.HDPE/HAPP/Fiber c7. Sulf.(2min)Pe1.HDPE/MAPP/Fiber cs. Sulf.(4min)Pel.HDPE/MAPP/Fiber SUMMARY AND CONCLUSION In sulfonation of HDPE resin, the effect of a longer reaction time and an increased surface area was shown to result in increased levels of sulfonation. However, the extent of sulfonation achieved was quite low and did not modify the dispersive and polar characteristics of the polymer to a level which would result in enhanced interfacial interaction between the HDPE and wood fibers with a concomitant increase in mechanical properties. The HDPE/wood fiber composite fabricated with MAPP as a coupling agent showed a statistically significant increase in tensile strength, modulus of elasticity, and flexural yield strength, but decreased in percent elongation at break and impact strength, as compared to the untreated composite. These findings could be attributed to the inclusion of MAPP resulting in increased interfacial adhesion between HDPE and wood fibers, with an associated increase in stiffness and brittleness but a decrease in toughness and flexibility of the resultant composite structures. The sulfonated HDPE based composite fabricated with MAPP exhibited little or no practical differences in mechanical properties, as compared to the non-sulfonated HDPE based composite fabricated with MAPP. Thus, sulfonation at the 58 59 achieved levels had little or no effect on enhancing the mechanical properties of the HDPE composite fabricated with MAPP. The composite fabricated with powdered HDPE exhibited statistically significant increases in tensile strength, modulus of elasticity, and flexural yield strength, but showed a decrease in percent elongation at break and impact strength, as compared to the pelletized HDPE based composite. This result may be attributed to the increased compatibility between HDPE and wood fibers. The composite fabricated with sulfonated powdered HDPE showed no significant differences of mechanical properties, when compared to that with non—sulfonated powdered HDPE. Thus, sulfonation at the achieved levels had little or no effect on enhancing the mechanical properties of the powdered HDPE composite. RECOMMENDATION FOR FURTHER RESEARCH In order to obtain conclusive results for enhanced interfacial interaction between HDPE and wood fibers with a concomitant increase in mechanical properties of surface sulfonated HDPE/wood fiber composites, the following investigations are proposed for further study: (i) a much longer reaction time or higher temperature in sulfonation, to achieve increased levels of sulfonation, which can effectively modify dispersive and non-dispersive energies on the HDPE surface; (ii) utilize powdered HDPE resin samples to obtain the increased levels of sulfonation and also the increased compatibility with wood fibers in compounding process. Additionally, .the effect of surface sulfonation of polypropylene (PP) on mechanical properties of PP/wood fiber composites should be considered. Sulfonation of PP has been found to easily modify the surface energy properties on PP surface, since the presence of tertiary carbons in the molecule obtains active sites for 803 insertion (Wangwiwatsilp, 1993). The effective modification of the surface energy properties of the PP may offer an opportunity to increase the interfacial interaction between PP and wood fibers . 60 APPENDIX A APPENDIX A Table 10. Results of DSC for Pelletized HDPE Resin Var. Tm AHf No. Type of HDPE (°C) (J/g) %crysta11inity 1 Pelletized 135.16 176.1 61.51 2 Pelletized 135.96 173.9 60.74 Mean 135.56 175.0 61.12 SD 0.57 1.6 0.54 Table 11. Results of DSC for Powdered HDPE Resin Var. Tm AHf No. Type of HDPE (°C) (J/g) %crysta11inity 1 Powdered 136.07 204.6 71.46 2 Powdered 136.17 200.9 70.17 Mean 136.12 202.8 70.81 SD 0.07 2.6 0.91 61 62 Figure 12. DSC Data for Pelletized HDPE Resin Sample: HDPE PELLETIZED, SAMPLE #2 [3 E3 (3 F119: BRHDPE.04 Size: 15.2000 mg Operator: BPR Method' IO‘C/MIN T0 200°C Run Date: S-Oct-SB 10:42 Comment: SGML/MIN N2 PURGE. 1 126.17’C o— 176.1.J/g . 1 g 3 ~1- E I o . LL a g -2- I -3— ‘ 135.16°C A T ' 150 200 C 50 10° . Genera] v4.1C DuPont 2200 Temperature ( 0 Samole’ PELLETIZED HDPE. SAMPLE #3 E) E3 (3 F112: BRHDPE 05 5122' 15.4000 m Operator: Ben Method' 10°C/MIN T0 200°C Run Date' S-Oct-QB 14 40 Comment SGML/MIN N2 PURSE 1 126.28°C 0' 173 93/9 3 ~1— E 3 D . LL :3 -2— I _3—. 135 96°C _4 , , . C 50 100 150 200 Genera] V4 1C DuPont 2200 Temoerature ("C 63 Figure 13. DSC Data for Powdered HDPE Resin Sample PONOEBED HOPE. #1 E3 F118 BRHOPE 01 5129 15 1000 mg [3 C: Operator BPR Methoo 10°C/MIN TO 300°C Run Date. l—OCt-QB 10 45 Comment' 50 ML/MIN N2 PURGE. 1 1 Ca 126.68°C 204.63/9 1 I 1 L__ I *1 3’ -1- E I o 4 LL 3.) a -2— r _J —-3-—1 1 136.07°C —4 - r . , I 0 50 100 200 Temperature (°C) General v4 1C DuPont 2200 Samole POWDEREO HDPE. #2 DSC File: BRHDPE02 SIZE. 16 3000 mg Operator: BPR Metnod' 10°C/MIN T0 300°C nun Date: 1—0ct-93 11:18 COmment: 50 ML/MIN N2 PURGE. 1 0- 126.55°C {\/-\_._ 200.9J/9 4 I l l 3‘ -1- E I 0 LL 5.! (O .. _. m 2 I -3— .( 136.17°C -4 Y Sb 7 oo '0 200 O 1 General V4.1C DuPont 2200 Temoerature (°C) APPENDIX B APPENDIX B Table 12 . Density Measurement Data (gm/ cm3) Comp. Replications No. 1 2 3 4 5 6 7 8 9 10 Cl 1.05 1.06 1.06 1.06 1.03 1.06 1.08 1.04 1.08 1.06 C2 1.10 1.08 1.08 1.05 1.07 1.06 1.08 1.05 1.02 1.06 C3 1.06 1.02 1.07 1.04 1.06 1.02 1.06 1.04 1.04 1.06 C4 1.07 1.09 1.04 1.09 1.07 1.03 1.08 1.04 1.03 1.09 C5 1.06 1.09 1.08 1.08 1.05 1.08 1.09 1.07 1.09 1.08 C6 1.09 1.06 1.12 1.05 1.04 1.04 1.09 0.99 1.02 1.11 C7 1.09 1.05 1.06 1.07 1.07 1.08 1.10 1.09 1.08 1.08 C8 1.06 1.07 1.07 1.09 1.10 1.06 1.06 1.08 1.09 1.09 64 65 Table 13. Tensile strength Data (MPa) Comp. Fiber Replications lo. Dir. 1 2 3 4 5 6 7 C1 Length 25.75 25.57 28.36 24.00 29.11 22.34 21.18 C1 Length 23.58 19.55 25.03 22.30 19.64 22.06 23.30 C1 Cross 9.46 10.11 10.71 11.10 11.31 11.63 10.92 C1 Cross 10.73 11.36 10.99 11.18 9.80 9.50 9.46 C2 Length 26.65 20.69 25.66 20.28 23.40 21.21 18.13 C2 Length 26.80 21.17 27.64 24.95 23.41 21.77 21.85 C2 Cross 10.69 10.90 11.06 11.56 11.24 11.16 11.21 C2 Cross 12.38 11.85 11.36 12.31 10.29 11.41 9.98 C3 Length 18.03 16.42 19.93 20.26 26.50 24.29 19.90 C3 Length 18.84 23.23 15.82 18.08 25.74 20.58 20.85 C3 Cross 10.56 11.78 11.40 10.65 11.81 11.09 C3 Cross 11.94 12.40 11.05 11.42 12.16 C4 Length 21.34 25.97 26.32 25.32 42.36 C4 Length 24.46 26.08 25.71 27.66 27.68 C4 Cross 19.35 19.75 20.93 23.18 23.05 C4 Cross 19.57 20.15 21.75 22.61 23.46 C5 Length 24.82 21.55 24.50 25.44 20.48 C5 Length 26.37 22.70 23.16 24.23 28.05 C5 Cross 19.72 19.16 21.64 17.68 19.99 C5 Cross 22.38 23.39 19.70 20.15 22.30 21.05 C6 Length 30.78 29.08 22.03 30.45 29.63 C6 Length 28.70 33.56 28.96 29.55 25.33 C6 Cross 20.61 20.39 20.32 21.81 21.95 C6 Cross 23.37 16.84 19.65 20.09 19.17 C7 Length 29.10 25.64 26.64 26.85 26.76 27.65 C7 Length 28.27 29.15 27.68 26.96 22.99 C7 Cross 17.62 17.61 17.71 16.91 17.80 C7 Cross 16.91 16.51 17.59 18.93 16.48 66 Table 13 . (cont ' d) Comp. Fiber Replications no. Dir. 1 2 3 4 5 6 C8 Length 22.44 31.78 29.21 20.91 19.84 C8 Length 36.84 20.57 28.27 27.69 23.25 C8 Cross 14.49 15.00 15.93 15.20 15.03 C8 Cross 15.18 15.40 15.51 15.95 14.51 P1 29.78 32.82 33.13 31.97 31.36 P1 30.83 29.74 29.78 29.06 28.41 P2 31.12 32.00 30.90 31.23 31.58 30.42 P2 30.81 31.41 30.81 31.07 30.03 31.18 P3 31.34 31.83 32.12 32.38 32.27 29.47 P3 30.48 30.13 31.32 29.87 30.79 P4 31.96 30.29 30.77 30.79 30.12 31.13 P4 30.83 29.74 29.78 29.06 28.41 Table 14. Modulus of Elasticity Data (MPa) Comp. Fiber Replications no. Dir. 1 2 3 4 5 6 7 C1 Length 2091.8 1838.8 1487.2 1390.6 1220.3 2481.4 2051.8 C1 Length 2243.5 1769.8 1175.5 1634.7 1428.6 1672.6 1734.0 C1 Cross 1717.4 2084.9 2050.5 1657.5 1893.3 2233.9 2091.8 C1 Cross 1370.0 1929.1 2080.1 2012.5 2107.0 1920.8 1931.2 C2 Length 2342.8 1294.1 763.9 1187.9 1088.0 1305.9 1608.5 C2 Length 1623.0 853.6 2322.8 1800.9 1725.7 1781.6 1559.6 C2 Cross 490.9 151.7 153.8 252.3 316.6 397.8 387.5 C2 Cross 133.1 255.8 183.4 226.1 96.5 126.9 226.1 C3 Length 1991.9 2099.4 1922.9 2206.3 2337.3 2019.4 2209.7 C3 Length 2005.0 1913.3 2531.7 2181.5 2173.2 2225.6 2280.0 C3 Cross 1803.6 1967.0 1856.7 1868.4 1945.0 1704.4 C3 Cross 2167.0 2048.4 1826.4 1962.9 1754.0 67 Table 14 . (cont ' d) Comp. Fiber Replications no. Dir. 1 2 3 4 5 6 C4 Length 1652.0 1496.1 1618.9 1697.5 2012.5 C4 Length 1836.7 2429.0 2259.4 2613.1 2420.0 C4 Cross 1505.8 2315.2 1680.2 1658.8 1800.9 C4 Cross 2373.1 2473.1 2290.4 2510.3 2514.5 C5 Length 1917.4 1938.8 1885.7 2104.2 1765.0 C5 Length 2098.0 2175.3 1991.2 '2104.9 2737.9 C5 Cross 2229.7 2294.5 1895.3 2246.3 2429.0 C5 Cross 2378.0 2493.1 2304.9 2206.3 2308.3 2360.7 C6 Length 2423.5 2135.3 2433.1 2416.6 2178.7 C6 Length 2160.1 2333.1 2049.1 2810.2 2336.6 C6 Cross 2551.0 2120.1 2435.2 2401.4 2264.9 C6 Cross 2574.4 2021.5 2521.4 2222.1 2668.2 C7 Length 2632.4 2531.7 2768.2 3360.4 1887.7 2235.2 C7 Length 2941.9 2611.0 2273.8 2411.7 2354.5 C7 Cross 2133.2 1771.9 2444.8 2148.4 2489.0 C7 Cross 2152.5 2124.2 2506.2 2080.8 2089.8 C8 Length 2221.4 3212.9 2909.5 2438.6 2235.2 C8 Length 2571.7 2253.2 2643.4 2673.0 2389.0 C8 Cross 2370.4 1971.2 1917.4 2265.6 2096.0 C8 Cross 2199.4 2282.1 2275.2 2335.9 1937.4 P1 697.7 729.5 727.4 653.6 1118.3 P1 1025.9 875.6 964.6 1045.9 1059.0 P2 1254.8 1345.8 1471.3 1395.5 1194.1 1238.3 P2 1361.0 1387.9 1271.4 1405.8 1236.9 1545.1 P3 1289.3 1237.6 1290.7 1261.7 1386.5 1221.0 P3 1065.2 1085.2 1128.7 1221.0 1442.4 P4 631.6 610.9 552.3 649.5 657.1 613.6 P4 1025.9 875.6 964.6 1045.9 1059.0 68 Table 15 . Percent Elongation at Break Data (% ) Comp. Fiber Replications no. Dir. 1 2 3 4 5 6 7 C1 Length 3.94 3.40 3.76 3.01 3.44 2.70 3.55 C1 Length 2.79 2.72 3.32 2.73 2.46 3.02 3.21 C1 Cross 1.16 1.13 1.38 1.61 1.46 1.49 2.16 Cl Cross 2.11 2.14 1.53 1.62 1.16 1.21 1.03 C2 Length 4.60 3.16 4.51 2.82 3.67 3.49 2.83 C2 Length 3.59 2.72 3.56 3.13 2.83 2.87 3.14 C2 Cross 1.89 2.41 2.19 2.79 2.27 2.62 3.12 C2 Cross 2.95 2.52 2.17 2.73 2.79 2.97 1.83 C3 Length 2.71 2.34 2.22 2.38 2.63 2.71 2.28 C3 Length 1.90 2.59 1.50 1.68 2.21 2.27 2.49 C3 Cross 1.14 1.22 1.05 1.04 1.25 1.10 C3 Cross 2.17 1.54 1.66 1.11 1.61 C4 Length 2.18 2.93 2.59 2.36 3.77 C4 Length 2.34 1.85 1.91 1.80 2.17 C4 Cross 2.28 1.67 2.88 2.36 2.44 C4 Cross 1.24 1.43 1.98 1.80 1.58 C5 Length 3.03 2.42 2.47 2.31 1.70 C5 Length 2.41 1.66 2.01 2.20 1.87 C5 Cross 1.57 1.53 1.92 1.39 1.34 C5 Cross 2.13 1.48 1.72 2.27 1.69 2.04 C6 Length 2.95 2.21 1.53 2.63 2.94 C6 Length 2.76 3.31 2.55 1.75 1.81 C6 Cross 1.73 1.72 2.12 1.73 1.93 C6 Cross 1.62 1.57 1.55 1.54 1.38 C7 Length 2.26 1.87 1.69 1.48 2.13 1.81 C7 Length 2.08 2.19 2.63 2.20 2.15 C7 Cross 1.48 1.41 1.26 1.27 1.08 C7 Cross 1.07 1.19 1.07 1.41 0.99 69 Table 15 . (cont 'd) Comp. Fiber Replications no. Dir. 1 2 3 4 5 6 C8 Length 1.66 1.59 1.94 1.29 1.52 C8 Length 2.37 1.64 2.17 2.08 1.88 C8 Cross 1.25 1.08 1.21 1.14 1.26 C8 Cross 1.12 0.95 1.01 1.18 1.07 P1 178.0 75.1 252.0 133.0 50.5 P1 37.5 23.9 43.1 24.1 26.5 4 P2 95.0 89.0 116.0 95.9 115.0 207.0 P2 219.0 273.0 141.2 382.0 294.0 196.7 P3 120.0 78.8 581.0 104.0 95.4 41.4 P3 18.0 36.6 116.0 24.6 105.0 P4 28.5 62.4 45.3 40.2 54.2 53.9 P4 37.5 23.9 43.1 24.1 26.5 70 Table 16 . Flexural Yield Strength Data (MPa) Comp. Fiber Replications no. Dir. 1 2 3 4 5 C1 Length 34.58 42.59 33.74 40.73 39.71 C1 Cross 29.31 28.83 31.64 28.26 27.80 C2 Length 35.42 42.84 36.64 34.47 46.64 C2 Cross 23.71 24.39 24.60 24.65 22.01 C3 Length 42.11 27.82 39.26 31.75 45.31 C3 Cross 23.66 22.08 22.01 23.63 22.01 C4 Length 49.76 41.16 47.94 50.32 52.63 C4 Cross 35.93 38.25 36.25 37.95 39.98 C5 Length 49.13 951.78 49.35 49.82 49.93 C5 Cross 41.42 38.49 39.64 46.01 41.15 C6 Length, 64.02 62.62 51.46 54.07 53.03 C6 Cross 34.08 37.91 38.09 37.02 36.91 C7 Lengthu' 59.65 49.55 52.41 60.62 50.90 C7 Cross 29.61 28.59 31.69 31.36 28.50 C8 Length 49.34 50.70 49.66 47.45 53.93 C8 Cross 27.08 27.59 28.43 27.02 26.88 P1 27.96 27.39 26.13 26.86 27.76 P2 30.02 30.36 29.76 29.83 30.20 P3 30.07 27.57 27.96 29.83 29.61 P4 26.17 26.39 27.93 27.96 28.14 71 Table 17. Flexural Modulus Data (MPa) Comp. Fiber Replications Mo. Dir. 1 2 3 4 5 C1 Length 11811.4 13226.8 8003.3 9154.9 9419.8 C1 Cross 6656.8 11279.2 7679.4 6324.7 8437.8 C2 Length 8322.2. 7551.5 13428.2 7079.2 11016.1 C2 Cross 5523.6 5368.7 4803.3 6069.4 4931.4 C3 Length 13190.4 10402.8 14353.2 10177.2 14905.9 C3 Cross 9980.0 6784.6 7240.2 7826.7 6271.2 C4 Length 17084.2 12378.9 15860.3 10135.2 13895.1 C4 Cross 12942.4 15176.8 8737.2 9129.6 7943.7 C5 Length 12961.1 14735.1 11468.9 9260.0 15137.7 C5 Cross 16810.2 13254.0 12572.3 12120.9 9208.6 C6 Length 22008.1 20487.8 10302.4 8397.6 12808.2 C6 Cross 17149.2 11740.2 11673.2 10244.4 16000.1 C7 Length 15563.3 13888.4 19018.6 18299.0 14406.1 C7 Cross 19145.6 13137.9 12066.3 12548.1 13403.3 C8 Length 12462.2 8878.6 17852.5 14418.0 20391.1 C8 Cross 10626.8 9401.2 11899.8 9281.8 8667.5 P1 4120.1 3409.6 3529.1 4501.7 3509.6 P2 4246.7 3835.5 3853.2 3307.8 3221.2 P3 3200.1 3836.8 3144.6 4249.7 3612.7 P4 6308.6 4008.6 8273.8 6380.3 4472.7 Table 18 . 72 Impact Strength Data (J/m) Comp. Fiber Replications lo. Dir. 1 2 3 4 5 C1 Length 41.56 52.65 45.18 60.82 60.87 C1 Length 47.10 53.13 51.11 53.56 60.12 C1 Cross 39.48 45.56 53.51 49.19 41.50 C1 Cross 54.73 51.53 50.68 42.84 C2 Length 49.93 60.76 58.31 55.32 60.92 C2 Length 60.49 57.56 38.25 43.32 56.97 C2 Cross 52.01 54.89 52.87 42.62 45.45 C2 Cross 63.00 59.21 41.82 54.89 47.26 C3 Length 49.99 50.36 60.55 64.07 54.73 C3 Length 57.61 60.01 49.19 55.59 57.03 C3 Cross 66.47 54.57 58.47 46.84 57.03 C3 Cross 36.33 49.56 51.43 50.36 51.59 C4 Length 35.05 31.79 30.67 36.65 31.10 C4 Length 28.70 42.46 29.18 35.32 C4 Cross 25.07 24.27 42.25 26.78 33.98 C4 Cross 35.05 37.50 30.89 29.29 26.19 C5 Length 31.63 40.28 31.10 27.85 36.44 C5 Length 29.39 36.49 31.10 32.97 C5 Cross 41.61 39.69 32.81 30.62 23.21 C5 Cross 32.54 25.98 35.32 36.44 25.98 C6 Length 32.54 34.73 32.17 33.50 30.14 C6 Length 29.66 29.66 36.17 33.34 C6 Cross 30.62 30.14 32.33 32.54 32.33 C6 Cross 29.39 29.66 29.66 29.93 C7 Length 48.81 40.92 44.28 43.48 38.94 C7 Length 39.58 52.87 38.94 45.56 46.84 C7 Cross 34.73 37.61 32.65 36.17 35.85 C7 Cross 35.32 42.20 39.58 37.45 37.29 73 Table 18 . (cont 'd) Comp. Fiber Replications Mo. Dir. 1 2 3 4 5 C8 Length 37.50 45.88 38.20 46.84 39.26 C8 Length 43.16 45.61 40.92 46.84 44.86 C8 Cross 29.29 42.46 45.08 39.58 42.89 C8 Cross 30.62 45.02 38.20 40.92 43.00 Pl 96.24 109.68 108.35 101.41 95.92 P1 98.37 98.85 100.98 97.57 98.74 P2 100.98 101.47 112.45 103.23 94.32 P2 121.42 99.70 102.37 88.93 122.70 P3 87.97 106.21 137.37 126.86 116.62 P3 116.08 108.35 109.57 88.66 108.03 P4 150.01 126.86 130.33 143.66 116.35 P4 126.91 120.35 117.90 132.57 121.31 APPENDIX C APPENDIX C Table 19. One-Way Analysis of Variance of Density Measurement Values for Composites Analysis of Variance Table Degree of Sum of Mean F F Source, Freedom Sggares Sggare Rgtio Probability Between groups 7 0.008 0.0011 2.2857 0.0368 Within groups 72 0.036 0.0005 Total 79 0.044 Standard Standard 95% Confidence Group Count Mean Deviation pgrror Interval for Mean C1 10 1.06 0.01 0.0032 1.0528 To 1.0672 C2 10 1.06 0.02 0.0063 1.0457 To 1.0743 C3 10 1.05 0.02 0.0063 1.0357 To 1.0643 C4 10 1.08 0.01 0.0032 1.0728 To 1.0872 C5 10 1.08 0.02 0.0063 1.0657 To 1.0943 C6 10 1.06 0.03 0.0095 1.0385 To 1.0815 C7 10 1.07 0.01 0.0032 1.0628 To 1.0772 C8 10 1.06 0.04 0.0126 1.0314 To 1.0886 Totgl 80 1.065 0.0236 0.0026 1.0597 To 1.0703 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 4.41 The value actually compared with Mean (J) - Mean (I) is 0.0158 x Range x Sqrt ( 1/N(I) + 1/N(J) ) No two groups are significantly different at the 0.05 level 74 75 Table 20. One-Way Analysis of Variance of Tensile Strength Values for Composites (Lengthwise Fiber Direction) Analysis of Variance Table Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Retio Probability Between groups 7 602.5361 86.0766 54.1604 0.0000 Within groups 85 135.0897 1.5893 Totel 92 737.6258 Standard Standard 95% Confidence Group Count Meen Deyietion Error Interval for Mean C1 14 23.70 2.11 0.5639 22.4817 To 29.9183 C2 14 23.11 1.17 0.3127 22.4345 To 23.7855 C3 14 20.61 0.22 0.0588 20.4830 To 20.7370 C4 11 27.06 0.07 0.0211 27.0130 To 27.1070 C5 10 26.08 1.76 0.5566 24.8210 To 27.3390 C6 10 27.29 1.38 0.4364 26.3028 To 28.2772 C7 10 24.13 1.09 0.3447 23.3503 To 24.9097 C8 10 28.81 0.58 0.1834 28.3951 To 29.2249 Totel 93 24.78 2.83 0.2936 24.1979 To 25.3642 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 4.39 The value actually compared with Mean (J) - Mean (I) is 0.8914 x Range x Sqrt ( 1/N(I) + 1/N(J) ) (*) Denotes pairs of group significantly different at the 0.05 level Group C1 C2 C3 C4 C5 C6 C7 C8 C1 * * * C2 C3 C4 C5 C6 C7 C8 * * **fi* #303?”- *1; ”I'M-It *I-fl-Il'l' til-filtflt 76 Table 21. One-Way Analysis of Variance of Tensile Strength Values for. Composites (Crosswise Fiber Direction) Analysis of (Variance Table Degree of Sum of Mean F . F Sourceg, Freedom Sgpares Sgpare Retio Probability Between groups 7 1674.7496 239.2499 726.4737 0.0000 Within groups 82 27.0051 0.3293 Totel 89 1701.7547 Standard Standard 95% Confidence Group Count yMeen Deyietion Error Interval for Mean Cl 14 10.59 0.23 0.0615 10.4572 To 10.7228 C2 14 11.24 0.18 0.0481 11.1361 To 11.3439 C3 11 11.50 0.41 0.1236 11.2246 To 11.7754 C4 10 17.41 ‘ 0.17 0.0538 17.2884 To 17.5316 C5 10 15.22 0.13 0.0411 15.1270 To 15.3130 C6 10 21.38 0.18 0.0569 21.2512 To 21.5088 C7 11 20.57 1.31 0.3950 19.6899 To 21.4501 C8 10 20.42 0.84 0.2656 19.8191 To 21.0209 Totel 90 15.59 4.37 0.4609 14.6696 To 16.5013 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 4.40 The value actually compared with Mean (J) - Mean (I) is 0.4058 x Range x Sqrt ( l/N(I) + 1/N(J) ) (*) Denotes pairs of group significantly different at the 0.05 level Group C1 C2 C3 C4 C5 C6 C7 C8 C]. 'k * * * 1: * C2 1: 'k * * * c3 * ~k * 4 'k 4- c4 * * t * a» * 4 C5 * * * *- 1: * * c5 * * at * * * * c7 * * t at 4 * C8 * 4 t * 77 Table 22. One-Way Analysis of Variance of Modulus of Elastisity Values for composites (Lengthwise Fiber Direction) Analysis of Variance Table Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Retio Probability Between groups 7 11490850.15 l641550.021 48.3563 0.0000 Within groups 85 2885492.949 33946.9759 Totel 92 14376343.1 Standard Standard 95% Confidence Group Count Mean Deviation Error Intepyel for Meen C1 14 1730.05 91.24 24.3894 1677.3696 To 1782.7304 C2 14 1518.44 209.70 56.0447 1397.3628 To 1639.5172 C3 14 2149.79 52.86 14.1274 2119.2695 To 2180.3105 C4 11 2543.94 35.83 10.8032 2519.8691 To 2568.0109 C5 10 2554.79 68.94 21.8007 2505.4733 To 2604.1067 C6 10 2003.50 435.75 137.7962 1691.7834 To 2315.2166 C7 10 2071.83 211.58 66.9075 1920.4749 To 2223.1851 C8 10 2327.62 14.43 4.5632 2317.2974 To 2337.9426 Totel 93 2076.74 395.30 40.9910 1995.3266 To 2158.1500 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 4.39 The value actually compared with Mean (J) - Mean (I) is 130.2823 x Range x Sqrt ( 1/N(I) + l/N(J) ) (*) Denotes pairs of group significantly different at the 0.05 level Group C1 C2 C3 C4 C5 C6 C7 C8 C1 * C2 * * -k a: a * c3 * *- C4 C5 C6 C7 'C8 it’d-#863636 I'd-$36!» 78 Table 23. One-Way Analysis of Variance of Modulus of Elastisity Values for composites (Crosswise Fiber Direction) Analysis of Variance Table Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Retio Probability Between groups 7 43962861.77 6280408.024 241.6535 0.0000 Within groups 82 2131123.587 25989.3120 Toteli 89 46093985.36 Standard Standard 95% Confidence Group Count Meen Deyietion Error Interval for Mean C1 14 1934.28 38.24 10.2201 1912.2009 To 1956.3591 C27 14 242.75 91.18 24.3689 190.1042 To 295.3958 C3 11 1904.62 66.61 20.0837 1859.8708 To 1949.3692 C4 10 2194.07 4.78 1.5116 2190.6506 To 2197.4894 C5 10 2165.04 57.92 18.3159 2123.6065 To 2206.4735 C6 10 2112.23 452.62 143.1310 1788.4453 To 2436.0147 C7 11 2280.41 86.91 26.2044 2222.0231 To 2338.7969 C8 10 2378.02 33.25 10.5146 2354.2344 To 2401.8056 Totel 90 1833.42 719.66 75.8588 1682.6852 To 1984.1448 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 4.40 The value actually compared with Mean (J) - Mean (I) is 113.9941 x Range x Sqrt ( 1/N(I) + l/N(J) ) (*) Denotes pairs of group significantly different at the 0.05 level Group C1 C2 C3 C4 C5 C6 C7 C8 C1 * t t * C2 * * 'k t * C3 * * C4 C5 C6 C7 C8 *fifififl-fi 79 Table 24. One-Way Analysis of Variance of Percent Elongation at Break Values for composites (Lengthwise Fiber Direction) Analysis of Variance Table Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Retio Probability Between groups 7 24.5694 3.5099 34.3764 0.0000 Within groups 85 8.6787 0.1021 Totel 92 33.2481 Standard Standard 95% Confidence Group Count Meen Deyietion Error Interval for Mean C1 14 3.15 0.36 0.0962 2.9421 To 3.3579 C2 14 3.35 0.33 0.0882 3.1595 To 3.5405 C3 14 2.28 0.27 0.0722 2.1241 To 2.4359 C4 11 2.06 0.27 0.0814 1.8786 To 2.2414 C5 10 1.81 0.30 0.0949 1.5954 To 2.0246 C6 10 2.39 0.53 0.1676 2.0109 To 2.7691 C7 10 2.21 0.25 0.0791 2.0312 To 2.3888 C8 10 2.44 0.01 0.0032 2.3932 To 2.4472 Tgpel 93 2.52 0.60 0.0623 2.3932 To 2.6408 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 4.39 The value actually compared with Mean (J) - Mean (I) is 0.2259 x Range x Sqrt ( 1/N(I) + l/N(J) ) (*) Denotes pairs of group significantly different at the 0.05 level Group C1 C1 C2 C3 C4 C5 C6 C7 C8 fifl'flblfiififl' C2 fififl'fl-IO-It C3 C4 * C5 C6 C8 80 Table 25. One-Way Analysis of Variance of Percent * Elongation at Break Values for composites (Crosswise Fiber Direction) Analysis of Variance Table Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 7 17.2699 2.4671 42.3691 0.0000 Within groups 82 4.7748 0.0582 Totel 89 22.0447 Standard Standard 95% Confidence Group Count Meen Deyietion Error Interval for Meen C1 14 1.51 0.04 0.0107 1.4869 To 1.5331 C2 14 2.52 0.07 0.0187 2.4796 To 2.5604 C3 11 1.38 0.34 0.1025 1.1516 To 1.6084 C4 10 1.22 0.11 0.0348 1.1413 To 1.2987 C5 10 1.13 0.09 0.0285 1.0656 To 1.1944 C6 10 1.97 0.51 0.1613 1.6052 To 2.3348 C7 11 1.72 0.24 0.0724 1.5588 To 1.8812 C8 10 1.69 0.22 0.0696 1.5326 To 1.8474 Totel 90 1.67 0.50 0.0525 1.5693 To 1.7778 Multiple Comparison Test Tukey—HSD procedure Range for the 0.05 level Table range: 4.40 The value actually compared with Mean (J) - Mean (I) is 0.1706 x Range x Sqrt ( 1/N(I) + 1/N(J) ) (*) Denotes pairs of group significantly different at the 0.05 level Group C1 C2 C3 C4 C5 C6 C7 C8 * C1 * * (:2 * t * 'k «k * c3 * * * C4 * * t * C5 * * t 1: C6 1: * C7 'k * C8 * 81 Table 26. One-Way Analysis of Variance of Flexural Yield Strength Values for composites (Lengthwise Fiber Direction) Analysis of Variance Table Degree of Sum of Mean F F Source Freedom Sggares Sgpare Retio Probability Between groups 7 2061.0964 294.4423 12.9177 0.0000 Within groups 32 729.3996 22.7937 Toteli 39 2790.4960 Standard Standard 95% Confidence. Group Count Mean Deviation yError Interval for Mean C1 5 38.27 3.91 1.7486 33.4152 To 43.1248 C2 5 39.20 5.28 2.3613 32.6441 To 45.7559 C3 5 37.25 7.28 3.2557 28.2108 To 46.2892 C4 5 54.63 5.14 2.2987 48.2480 To 61.0120 C5 5 50.22 2.38 1.0644 47.2649 To 53.1751 C6 5 48.36 4.36 1.9499 42.9464 To 53.7736 C7 5 50.00 1.05 0.4696 48.6963 To 51.3037 C8 5 57.04 5.83 2.6073 49.8012 To 64.2788 Totel 40 46.87 8.46 1.3375 44.1660 To 49.5765 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 4.58 The value actually compared with Mean (J) - Mean (I) is 3.3759 x Range x Sqrt ( 1/N(I) + 1/N(J) ) (*) Denotes pairs of group significantly different at the 0.05 level Group C1 C2 C3 C4 C5 C6 C7 C8 C1 * * * c2 * * C3 * 'k '4' C4 * * * c5 * * c5 * * c7 * * ca * * 82 Table 27. One-Way Analysis of Variance of Flexural Yield Strength Values for composites (Crosswise Fiber Direction) Analysis of Variance Table Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 7 1610.0478 230.0068 89.6612 0.0000 Within groups 32 82.0892 2.5653 Toteli 39 1692.1370 Standard Standard 95% Confidence Group Count Meen Deygetion Error Interval for Mean C1 5 29.17 1.50 0.6708 27.3075 To 31.0325 C2 5 23.87 1.11 0.4964 22.4918 To 25.2482 C3 5 22.68 0.88 0.3935 21.5874 To 23.7726 C4 5 29.95 1.51 0.6753 28.0751 To 31.8249 C5 5 27.40 0.64 0.2862 26.6053 To 28.1947 C6 5 37.67 1.64 0.7334 35.6337 To 39.7063 C7 5 41.32 2.88 1.2880 37.7441 To 44.8959 C8 5 36.80 1.61 0.7200 34.8010 To 38.7990 Totel 40 31.11 6.59 1.0415 29.0009 To 33.2141 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 4.40 The value actually compared with Mean (J) - Mean (I) is 1.1254 x Range x Sqrt ( 1/N(I) + 1/N(J) ) (*) Denotes pairs of group significantly different at the 0.05 level Group C1 C2 C3 C4 C5 C6 C7 C8 C1 * 'k t t * C2 * 1: 1: * c3 * t * t * c4 * * * 'k a: * C5 * t * * * * c5 * * * * c7 * t 'k t * C8 * * 'k * 83 Table 28. One-Way Analysis of Variance of Flexural Modulus Values for composites (Lengthwise Fiber Direction) Analysis of Variance Table Degree of Sum of Mean F F Source Freedom Sgpares Sgpare pEetio Probability Between groups 7 181313884.9 25901983.55 2.1721 0.0638 Within groups 32 381588770.0 11924649.06 Totel 39 562902654.8 . Standard Standard 95% Confidence Group Count Meen Deviation Error Interval for Mean C1 5 10323.23 2133.58 954.1660 7674.0835 To 12972.3765 C2 5 9599.44 2630.12 1176.2254 6333.7676 To 12865.1124 C3 5 13190.40 2724.26 1218.3261 9807.8393 To 16572.9607 C4 5 16235.08 2308.18 1032.2495 13369.1425 To 19101.0175 C5 5 14800.49 4506.99 2015.5872 9204.4135 To 20396.5665 C6 5 13870.73 2759.76 1234.2022 10444.0909 To 17297.3691 C7 5 12712.56 2423.88 1083.9921 9702.9643 To 15722.1557 C8 5 14800.83 6113.41 2734.0001 7210.1520 To 22391.5080 Total 40 13191.60 3799.13 600.6955 11976.5737 To 14406.6163 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 4.58 The value actually compared with Mean (J) - Mean (I) is 2441.7872 x Range x Sqrt ( 1/N(I) + 1/N(J) ) No two groups are significantly different at the 0.05 level 84 Table 29. One-Way Analysis of Variance .of Flexural Modulus Values for composites (Crosswise Fiber Direction) Analysis of Variance Table Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 7 333931816.2 47704545.17 8.9728 0.0000 Within groups 32 170131139.2 5316598.101 Totel 39 504062955.4 Standard Standard 95% Confidence Group Count Mean Deviation Error Interval for Mean C1 5 8075.58 1976.75 884.0295 5621.1605 To 10529.9995 C2 5 5339.27 505.34 225.9949 4711.8177 To 5966.7223 C3 5 7620.57 1438.19 643.1781 5834.8502 To 9406.2898 C4 5 14060.24 2889.86 1292.3847 10472.0631 To 17648.4169 C5 5 9975.42 1289.27 576.5791 8374.6058 To 11576.2342 C6 5 10785.94 3120.44 1395.5032 6911.4648 To 14660.4152 C7 5 12793.20 2724.84 1218.5855 9409.9191 To 16176.4809 C8 5 13361.38 3020.94 1351.0054 9610.4484 To 17112.3116 Totelw 40 10251.45 3595.09 568.4341 9101.6836 To 11401.2164 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table ranges: 4.58 The value actually compared with Mean (J) - Mean (I) is 1630.4291 x Range x Sqrt ( 1/N(I) + 1/N(J) ) (*) Denotes pairs of group significantly different at the 0.05 level Group C1 C2 C3 C4 C5 C6 C7 C8 C1 * C2 * 1: C3 * C4 * 'k * C5 C6 C7 C8 * 85 Table 30. One-Way Analysis of Variance of Impact Strength Values for composites (Lengthwise Fiber Direction) Analysis of Variance Table Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Retio Probability Between groups 7 6499.4524 928.4932 35.3048 0.0000 Within groups 69 1814.6527 26.2993 Totel 76 8314.1051 Standard Standard 95% Confidence Group Count Meen Deviation Error Interval for Mean C1 10 52.61 6.69 2.1156 47.8243 To 57.3957 C2 10 54.18 7.86 2.4856 48.5573 To 59.8027 C3 10 55.91 4.96 1.5685 52.3618 To 59.4582 .C4 10 44.02 4.63 1.4641 40.7079 To 47.3321 C5 10 42.91 3.65 1.1542 40.2989 To 45.5211 C6 9 33.44 4.39 1.4633 30.0656 To 36.8144 C7 9 33.03 3.96 1.3200 29.9861 To 36.0739 C8 9 32.43 2.29 0.7633 30.6698 To 34.1902 Tote; 77 43.98 10.46 1.1919 41.6053 To 46.3532 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 4.42 The value actually compared with Mean (J) - Mean (I) is 3.6262 x Range x Sqrt ( 1/N(I) + 1/N(J) ) (*) Denotes pairs of group significantly different at the 0.05 level Group C1 C2 C3 C4 C5 C6 C7 C8 C1 * t t a: C2 * 'k * 1' c3 * * * c4 * * * 1: 1: * (:5 'k 4 t * t 4 C6 4 t * c7 * 4 * C8 * * * 86 Table 31. One-Way Analysis of Variance of Impact Strength Values for composites (Crosswise Fiber Direction) Analysis of Variance Table Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 7 5557.9097 793.9871 24.6166 0.0000 Within groups 70 2257.7875 32.2541 Totel 77 7815.6972 Standard Standard 95% Confidence Group Count yMeen Deyietion pError Interval for Mean C1 9 47.67 5.51 1.8367 43.4346 To 51.9054 C2 10 51.40 7.02 2.2199 46.3782 To 56.4218 C3 10 52.26 7.91 2.5014 46.6015 To 57.9185 C4 10 36.88 2.65 0.8380 34.9843 To 38.7757 C5 10 39.71 5.58 1.7646 35.7183 To 43.7017 C6 10 31.13 5.95 1.8816 26.8736 To 35.3864 C7 10 32.42 6.08 1.9227 28.0706 To 36.7694 C8 9 30.73 1.30 0.4333 29.7307 To 31.7293 Totel 78 40.30 10.07 1.1408 38.0310 To 42.5741 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 4.42 The value actually compared with Mean (J) - Mean (I) is 4.0159 x Range x Sqrt ( 1/N(I) + 1/N(J) ) (*) Denotes pairs of group significantly different at the 0.05 level Group C1 C2 C3 C4 C5 C6 C7 C8 * c1 c2 * * c3 * * C4 * 'k * C5 * ‘k t * C6 * 'k * c7 * * C8 * * * 87 Table 32. One-Way Analysis of Variance of Tensile Strength Values for Matrix Materials Analysis of Variance Table Degree of Sum of Mean F F Sourcefi Freedom Sgpares Sgpare Retio Probability Between groups 3 5.3682 1.7894 1.9391 0.1388 Within groups 40 36.9108 ' 0.9228 Totel 43 42.2790 Standard Standard 95% Confidence Group Count Meen Deyietion Error Interval for Mean P1 10 30.69 1.59 0.5028 29.5526 To 31.8274 P2 12 31.05 0.23 0.0664 30.9039 To 31.1961 P3 11 31.04 0.74 0.2231 30.5429 To 31.5371 P4 11 30.20 0.90 0.2714 29.5954 To 30.8046 Tgpel 44 30.75 0.99 0.1495 30.4517 To 31.0546 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 3.79 The value actually compared with Mean (J) - Mean (I) is 0.6793 x Range x Sqrt ( 1/N(I) + 1/N(J) ) No two groups are significantly different at the 0.05 level 88 Table 33. One-Way Analysis of Variance of Modulus of Elasticity Values for Matrix Materials Analysis of Variance Table Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Retio Probability Between groups 3 2273044.229 757681.4097 31.6631 0.0000 Within groups 40 957180.3940 23929.5098 Totel 43 3230224.623 Standard Standard 95% Confidence Group Count Meen Deviation Error Interval for Meen P1 10 889.75 147.72 46.7132 784.0775 To 995.4225 P2 12 1342.32 36.32 10.4847 1319.2434 To 1365.3966 P3 11 1234.81 65.51 19.7520 1190.7998 To 1278.8202 P4 11 806.67 265.21 79.9638 628.4995 To 984.8405 Totel 44 1078.67 274.08 41.3196 995.3443 To 1162.0020 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 3.79 The value actually compared with Mean (J) - Mean (I) is 109.3835 x Range x Sqrt ( 1/N(I) + 1/N(J) ) (*) Denotes pairs of group significantly different at the 0.05 level Group P1 P2 P3 P4 p1 * * P2 P3 P4 * * 89 Table 34. One-Way Analysis of Variance of Percent Elongation at Break Values for Matrix Materials Analysis of Variance Table Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 3 129908.0811 43302.6937 8.3270 0.0002 Within groups 40 208010.3334 5200.2583 Totel 43 337918.4145 Standard Standard 95% Confidence Group Count Meen Deviation pError Interval for Meen P1 10 84.37 75.45 23.8594 30.3963 To 138.3437 P2 12 185.32 92.87 26.8093 126.3132 To 244.3268 P3 11 115.07 77.82 23.4636 62.7898 To 167.3502 P4 11 39.22 11.59 3.4945 31.4337 To 47.0063 Totel 44 108.29 88.65 13.3643 81.3377 To 135.2409 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 3.79 The value actually compared with Mean (J) - Mean (I) is 109.3835 x Range x Sqrt ( 1/N(I) + 1/N(J) ) (*) Denotes pairs of group significantly different at the 0.05 level Group P1 P2 P3 P4 P1 * P2 * * P3 P4 * 90 Table 35. One-Way Analysis of Variance of Flexural Yield Strength Values for Matrix Materials Analysis of Variance Table Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 3 27.9385 9.3128 13.1393 0.0001 Within groups 16 11.3404 0.7088 Toteli 19 39.2789 Standard Standard 95% Confidence Group Count Mean Deviation Error Interval for Mean P1 5 27.22 0.74 0.3309 26.3012 To 28.1388 P2 5 30.03 0.25 0.1118 29.7196 To 30.3404 P3 5 29.01 1.15 0.5143 27.5821 To 30.4379 P4 5 27.32 0.95 0.4249 26.1404 To 28.4996 Totel 20 28.40 1.44 0.3215 27.7221 To 29.0679 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 4.04 The value actually compared with Mean (J) - Mean (I) is 0.5953 x Range x Sqrt ( 1/N(I) + 1/N(J) ) (*) Denotes pairs of group significantly different at the 0.05 level Group P1 P2 P3 P4 P1 'k * P2 * * P3 * * P4 * * 91 Table 36. One-Way Analysis of Variance of Flexural Modulus Values for Matrix Materials Analysis of Variance Table Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 3 17986500.18 5995500.059 6.7941 0.0036 Within groups 16 14119389.08 882461.8175 Totel 19 32105889.26 Standard Standard 95% Confidence Group Count Meen Deviation Error Interval for Mean P1 5 3814.03 475.39 212.6009 3223.7649 To 4404.2951 P2 5 3692.87 425.28 190.1910 3164.8237 To 4220.9163 P3 5 3608.77 459.70 205.5841 3037.9863 To 4179.5537 P4 5 5888.80 1706.36 763.1074 3770.1086 To 8007.4914 Totel 20 4251.12 1299.92 290.6702 3642.737? To 4859.4973 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 4.04 The value actually compared with Mean (J) - Mean (I) is 664.2521 x Range x Sqrt ( 1/N(I) + 1/N(J) ) (*) Denotes pairs of group significantly different at the 0.05 level Group P1 P2 P3 P4 P1 P2 * P3 * P4 * * t 92 Table 37. One-Way Analysis of Variance of Impact Strength Values for Matrix Materials Analysis of Variance Table Degree of Sum of Mean F F Source Freedom Squares Sgpare Ratio Probability Between groups 3 4574.6060 1524.8687 12.3415 0.0000 Within groups 36 4448.0367 123.5566 Totel 39 9022.6427 Standard Standard 95% Confidence Group Count Mean Deviation Error Interval for Mean P1 10 100.61 4.77 1.5084 97.1977 To 104.0223 P2 10 104.76 10.94 3.4595 96.9340 To 112.5860 P3 10 110.57 15.17 4.7972 99.7180 To 121.4220 P4 10 128.62 11.03 3.4880 120.7296 To 136.5104 Totel 40 111.14 15.21 2.4049 106.2755 To 116.0045 Multiple Comparison Test Tukey-HSD procedure Range for the 0.05 level Table range: 3.81 The value actually compared with Mean (J) — Mean (I) is 7.8599 x Range x Sqrt ( 1/N(I) + 1/N(J) ) (*) Denotes pairs of group significantly different at the 0.05 level Group P1 P2 P3 P4 P1 * P2 P3 * p4 * t * 93 Table 38. One Way Analysis of Variance of Mechanical Property Values for Composites with Lengthwise Fiber Direction vs. Crosswise Fiber Direction A. Composite #1 (C1) 1. Tensile Strength Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 1 1203.1047 1203.1047 534.1197 0.0000 Within groups 26 58.5650 2.2525 Totel 27 1261.6697 2 . Modulus of Elasticity Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 1 291969.2503 291969.2503 59.6645 0.0000 Within groups 26 127231.4576 Total 27 419200.7079 3 . Percent Elongation at Break Degree of Sum of Mean F F Source Freedom Sgpares Square Retio Probability Between groups 1 18.8272 18.8272 287.0000 0.0000 Within groups 26 0.0656 0.0656 Totel 27 0.044 4. Flexural. Yield. Strength Degree of Sum of Mean F F Source Freedom Sgpares Squepe Retio Probability Between groups 1 207.0250 207.0250 23.6086 0.0013 Within groups 8 70.1524 8.7691 Total 9 277.1774 5 . Flexural Modulus Degree of Sum of Mean F F Source Freedom Sgpares Squepe Ratio Probability Between groups 1 12629826.31 12629826.31 2.9859 0.1223 Within groups 8 33838816.72 4229852.089 Totel 9 46468643.02 6. Impact Strength Degree of Sum of Mean F F Source;, Freedom Sgpares Squepe Retio Probebilitv Between groups 1 115.5960 115.5960 3.0435 0.0991 Within groups 17 645.6857 37.9815 Total 18 761.2817 94 B. Composite #2 (C2) 1. Tensile Strength Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 1 984.6172 984.6172 1405.2911 0.0000 Within groups 26 18.2169 0.7006 Total 27 1002.8341 2. Modulus of Elasticity Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 1 11391694.83 11391694.83 435.7298 0.0000 Within groups 26 679742.4712 26143.9412 Total 27 12071437.3O 3. Percent Elongation at Break Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 1 4.8223 4.8223 84.7504 0.0000 Within groups 26 1.4794 0.0569 Total 27 6.3017 4. Flexural Yield Strength Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 1 587.5222 587.5222 40.3650 0.0002 Within groups 8 116.4420 14.5553 Total 9 703.9642 5. Flexural Modulus Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 1 45372621.07 45372621.07 12.6511 0.0074 Within groups 8 28691598.92 3586449.865 Total 9 74064219.99 6. Impact Strength Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 1 38.6420 38.6420 0.6959 0.4151 Within groups 17 999.5400 55.5300 Total 18 1038.1820 95 C. Composite #3 (C3) 1. Tensile Strength Degree of Sum of Mean F F Source_ Freedom Sgpares Sgpare Ratio Probability Between groups 1 511.2313 511.2313 5089.7415 0.0000 Within groups 23 2.3102 0.1004 Totel 24 513.5415 2. Modulus of Elasticity Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Retio Probability Between groups 1 370267.3060 370267.3060 105.5373 0.0000 Within groups 23 80693.2558 3508.4024 Totel 24 450960.5618 3 . Percent Elongation at Break Degree of Sum of Mean F F Source, Freedom Sgpares Sgpare Retio Probability Between groups 1 4.9896 4.9896 54.5519 0.0000 Within groups 23 2.1037 0.0915 Topel 24 7.0933 4. Flexural. Yield. Strength Degree of Sum of Mean F F Source ‘ Freedom Sgpares Sgpare Retio Probability Between groups 1 530.7123 530.7123 19.7391 0.0022 Within groups 8 215.0912 26.8864 Totel 9 745.8035 5 . Flexural Modulus Degree of Sum of Mean F F Sourcefi Freedom Sgpares Sgpare Retio Probability Between groups 1 77557515.57 77557515.57 16.3451 0.0037 Within groups 8 37959932.09 4744991.512 Totelp, 9 115517447.7 6. Impact. Strength Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 1 66.6125 66.6125 1.5283 0.2323 Within groups 18 784.5273 43.5848 Totel 19 851.1398 96 D. Composite #4 (C4) 1. Tensile Strength Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Retio Probabilitv Between groups 1 48.7845 487.7845 29983.5197 0.0000 Within groups 19 0.3091 0.0163 Totel 20 488.0936 2 . Modulus of Elasticity Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 1 641190.0885 641190.0885 933.9969 0.0000 Within groups 19 13043.5246 686.5013 Total 20 654233.6131 3 . Percent Elongation at Break Degree of Sum of Mean F F Source. Freedom Sgpares Sgpare Retio Probability Between groups 1 3.6960 3.6960 83.8095 0.0000 Within groups 19 0.8379 0.0441 Totel 20 4.5339 4. Flexural Yield. Strength Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Retio Probability Between groups 1 1522.7560 1301.8810 428.6734 0.0000 Within groups 8 114.7988 3.0370 Totel 9 1637.5548 5 . Flexural Modulus Degree of Sum of Mean F F Source Freedom Sgpares Sgpare Ratio Probability Between groups 1 11824822.56 11824822.56 1.7289 0.2250 Within groups 8 54715942.93 6839492.866 Total 9 66540765.49 6. Impact. Strength Degree of Sum of Mean F F Sourcepi Freedom Sgpares Sgpare pRetio Probebilitv Between groups 1 254.8980 254.8980 17.9131 0.0005 Within groups 18 256.1346 14.2297 _ Total 19 511.0326 97 E. Composite #5 (C5) 1. Tensile: Strength Degree of Sum of Mean F F Source, Freedom Sggares Sgeare Ratio Probability Between groups 1 589.6980 589.6980 378.6791 0.0000 Within groups 18 28.0305 1.5573 Totel 19 617.7285 2. Modulus of Elasticity Degree of Sum of Mean F F Source Freedom Sggares Sggare Retio Probability Between groups 1 759525.3125 759525.3125 187.3648 0.0000 Within groups 18 72967.0500 4053.7250 Totel 19 832492.3625 3 . Percent Elongation at Break Degree of Sum of Mean F F Source Freedom Sgeares Sgeare Retio Probebilitv Between groups 1 2.3120 2.3120 47.1356 0.0000 Within groups 18 0.8829 0.0490 Totel 19 3.1949 4. Flexural Yield Strength Degree of Sum of Mean F F Sourcee Freedom Sgeares Sgeare Ratio Probability Between groups 1 1301.8810 1301.8810 428.6734 0.0000 Within groups 8 24.2960 3.0370 Totel 9 1326.1770 5 . Flexural Modulus Degree of Sum of Mean F F Source Freedom Squares Sggare Retio Probability Between groups 1 58203251.26 58203251.26 5.2972 0.0503 Within groups 8 87900703.97 10987588.00 Totel 9 146103955.2 6. Impact. Strength Degree of Sum of Mean F F Source Freedom Sggares Sgeare Ratio Probability Between groups 1 51.2000 51.2000 2.3033 0.1465 Within groups 18 400.1301 22.2295 Total 19 451.3301 98 F . Composite # 6 (C6) 1. Tensile Strength Degree of Sum of Mean F F Source, Freedom Sgeares Sgeare Retio Probebilitv Between groups 1 174.6405 174.6405 180.3392 0.0000 Within groups 18 17.4312 0.9684 Totel 19 192.0717 2. Modulus of Elasticity Degree of Sum of Mean F F Source Freedom Sgeares Squege Retio Probability Between groups 1 59111.0645 59111.0645 0.2995 0.5909 Within groups 18 3552686.342 197371.4635 Totel 19 3611797.407 3 . Percent Elongation at Break Degree of Sum of Mean F F Sourceee, Freedom Sggares Sggare Ratio Probability Between groups 1 0.8820 0.8820 3.2606 0.0877 Within groups 18 4.8690 0.2705 Totel 19 5.7510 4. Flexural Yield Strength Degree of Sum of Mean F F Sourcey, Freedom Sgeares Sgeage Ratio Probability Between groups 1 285.6903 285.6903 26.3319 0.0009 Within groups 8 86.7968 10.8496 Totel 9 372.4871 5 . Flexural Modulus Degree of Sum of Mean F F Source, Freedom Squares Sggare Retio Probability Between groups 1 23789823.36 23789823.36 2.7418 0.1363 Within groups 8 69413684.20 8676710.526 Totel 9 93203507.57 6. Impact, Strength Degree of Sum of Mean F F Sourceyi Freedom Sggares Sggare Ratio Probability Between groups 1 25.2763 25.2763 0.9088 0.3538 Within groups 18 472.7993 27.8117 Totel 19 498.0756 99 G. Composite #7 (C7) 1. Tensile Strength Degree of Sum of Mean F F Source Freedom Sggares §geare Retio Probability Between groups 1 66.3855 66.3855 45.2836 0.0000 Within groups 19 27.8539 1.4660 Totel 20 94.2394 2. Modulus of Elasticity Degree of Sum of Mean F F Source Freedom Sgeares Sgeare Retio Probability Between groups 1 227886.5621 227886.5621 9.0501 0.0072 Within groups 19 478428.3486 25180.4394 Totel 20 706314.9107 3 . Percent Elongation at Break Degree of Sum of Mean F F Source Freedom Sggares Sggare Ratio Probability Between groups 1 1.2577 1.2577 20.9887 0.0002 Within groups 19 1.1385 0.0599 Totel 20 2.3962 4. Flexural Yield. Strength Degree of Sum of Mean F F Source, Freedom Sggares Sgeare Retio Probability Between groups 1 188.3560 188.3560 40.0890 0.0002 Within groups 8 37.5876 4.6984 Totel 9 225.9436 5 . Flexural Modulus Degree of Sum of Mean F F Source Freedom Sggares Sggare Ratio Probability Between groups 1 16257.024 16257.0240 0.0024 0.9618 Within groups 8 53199789.12 6649973.64 Totel 9 53216046.14 6. Impact. Strength Degree of Sum of Mean F F Sourceyi Freedom Sguares Sggare Ratio Probability Between groups 1 1.7626 1.7626 0.0654 0.8012 Within groups 17 458.1504 26.9500 Totel, 18 459.9130 100 H. Composite #8 (C8) 1. Tensile Strength Degree of Sum of Mean F F Source Freedom Sggares Sgeare Retio Probebilitv Between groups 1 351.1220 351.1220 673.9386 0.0000 Within groups 18 9.3780 0.5210 Totel 19 360.5000 2. Modulus of Elasticity Degree of Sum of Mean F F Source Freedom Sggares Sgeare Ratio Probability Between groups ‘ 1 12700.8000 12700.8000 19.3346 0.0003 Within groups 18 11824.0866 656.8937 Totel 19 24524.8866 3 . Percent Elongation at Break Degree of Sum of Mean F F Source, Freedom Sgeares Sgeare Retio Probability Between groups 1 2.8125 2.8125 115.9794 0.0000 Within groups 18 0.4365 0.0243 Totel 19 3.2490 4. Flexural Yield. Strength Degree of Sum of Mean F F Source Freedom Sggares Sggare Retio Probebility Between groups 1 1024.1440 1024.144 55.9932 0.0001 Within groups 8 146.3240 18.2905 Totel 9 1170.4680 5 . Flexural Modulus Degree of Sum of Mean F F Source Freedom Sgeares Sguare Ratio Probability Between groups 1 5180040.756 5180040.756 0.2228 0.6495 Within groups 8 185999441.2 23249930.16 Totel 9 191179482.1 6. Impact. Strength Degree of Sum of Mean F F Sourceyy Freedom Sgeares Square Retio Probability Between groups 1 4087.8882 4087.8882 1179.0681 0.0000 Within groups 16 55.4728 3.4671 Total 17 4143.3610 BIBLIOGRAPHY Agarwal, B. D. and Broutman, L. J., Analysis and Performance of Fiber Composites, John Wiley and Sons, Inc., 1980. ASTM Standard D 256—87, “Standard Test Methods for Impact Resistance of Plastics and Electrical Insulating Materials", Annual Book of ASTM Standards, Philadelphia, PA, pp. 57-73, 1988. 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