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This is to certify that the
thesis entitled
Effect of Ethanol Vapor on the Oxygen
Permeability of Packaging Polymer Films.
presented by

Sriprinya Ampolsak

has been accepted towards fulfillment
of the requirements for

Master degree in Packaqlnq

 

 

 

 

 

 

 

Major professor

Date 2-28-92

0.7639 MS U is an Affirmative Action/Equal Opportunity Institution

 

 

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MSU is An Atfinnetive ActiorVEquei Opportunity Institution

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*-

EFFECT OF ETHANOL VAPOR ON THE OXYGEN PERMEABILITY
OP PACKAGING POLYMER FILMS

BY
Sriprinya Ampolsak

A THEBIS
Submitted to Michigan State University
in the partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

School of Packaging

1992

{88- 3/85

ABSTRACT

EFFECT OP ETHANOL VAPOR ON TEE OXYG’I PERNEAEILITY
OP PACKAGING POLYNER EILNB

sy
Sriprinya Ampolsak

In this study, the steady state oxygen permeance of selected
films were determined under 0 ppm, 1 ppm and 7 ppm ethanol
vapor conditions. The oxygen permeability test were carried
out by using a modified Oxtran 100 permeability'testeru This
modification included the use Of tenax as ethanol adsorbent
which prevent ethanol vapor from exposing to the coulometer
sensor of the Oxtran. The result revealed that there was no
significant effect of ethanol vapor in the concentration range
of 0-1 ppm (wt/vol) on the oxygen permeability of selected

polymer film within 24 hour period.

To My Family .

iii

ACKNOWLEDGMENTS

I would like to gratefully thank to my major professor, Dr.
Ruben Hernandez, and my committee, Dr. Jack Gaicin and Dr. A.

Cameron for the support and guidance.

I feel especially thankful to Dr. Heidi Hoojjat and Dr. Rafael

Gavara for the kindness and friendship.

Finally, I would like to thank Ms. Linda K. Graesser,

Ms. Supawadee Thewasano, Mr. Myung Hoon Lee, Mr. Phillip
Neuberger, Mr. Kitti Wangwiwatsilp, Mr. Sorawit.Narupiti, and
all my friends for the help and support throughout the
difficult time.

iv

TABLE OE CONTENTS

Page
LI ST OF TABLES O O O O O O O O O O 0 O O O O O C O 0 v 1

LIST OF FIGURES . . . . . . . . . . . . . . . . . . ix
INTRODUCTION . . . . . . . . . . . . . . . . . . . . 1

LITERATURE REVIEW . . . . . . . . . . . . . . . . . 5

MATERIAL AND METHOD . . . . . . . . . . . . . . . . 26
RESULT AND DISCUSSION . . . . . . . . . . . . . . . 44
CONCLUSIONS . . . . . . . . . . . . . . . . . . . . 53
BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . 54
APPENDICES

Appendix 1 - Ethanol Calibration Curve
for the GC 0 O O O O O O O O O O O 5 6

Appendix 2 - Determination of Equilibrium

' Concentration of Ethanol in the
Head-space e e e e e e e e e e e e 6 1

Appendix 3 - Oxyen Absorptivity of Tenax . . . 64

Appendix 4 - Ethanol Sorption Capacity of Tenax 66

Appendix 5 - Calculation for Amount of Tenax for
Each Concentration of Ethanol
Condition . . . . . . . . . . . . 70

Appendix 6 - Determination of the Conversion
Factor for the Oxtran . . . . . . 72

Appendix 7 - Oxygen Permeance Data under 0 ppm
and 1 ppm Ethanol Vapor . . . . . 73

Appendix 8 - Determination of the Repeatability of
the Experiment . . . . . . . . . . 98

Appendix 9 - Activation Energy of Polymer Films 99

LIST OE TABLES

'Table Page

1. Ethanol Sorption Data of Polymer Films . . . . . . . 24

2. Permeability of Films Available for Packaging

FreSh PrOduce O O O O O O O O O O O O O O O O O O O 2 5

3. Oxygen Permeance of Polymer Film Samples at
0 ppm and 1 ppm Ethanol Vapor . . . . . . . . . . . 50

4. Oxygen Permeance of Polymer Film Samples at
0 ppm and 7 ppm Ethanol Vapor . . . . . . . . . . . 51

5. Normalized Values of Oxygen Permeance of Polymer
Polymer Films at 24 “C . . . . . . . . . . . . . . . 52

6. Ethanol Calibration Data for CC (1) . . . . . . . . 57
7. Ethanol Calibration Data for CC (2) . . . . . . . . 59

8. Equilibrium Concentration of Ethanol
Head-space O O O O O O O O O O O O O O O O O O O O O 62

9. Ethanol Sorption Capacity Data . . . . . . . . . . . 68

10. Oxygen Permeance Data of Polystyrene
0 ppm Ethano 1 O O O O O O O O O O O O O O O O O o O 7 3

11. Data of Polystyrene

O I O O O O O O O O O O O O O I O O 74

Oxygen Permeance
1 ppm Ethanol .

12.

13.

14.

15.

Oxygen Permeance
0 ppm Ethanol .

Oxygen Permeance
1 ppm Ethanol .

Oxygen Permeance
0 ppm Ethanol .

Oxygen Permeance
1 ppm Ethanol .

Data of

Data of

Data of

Data of

Saranex

Saranex

PET 0.7

PET 0.7

vi

2 mil

75

76

77

78

LIST OP TABLES (CONTINUED)

Table

16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.

31.

Oxygen Permeance
0 ppm Ethanol .

Oxygen Permeance
1 ppm Ethanol .

Oxygen Permeance
0 ppm Ethanol .

Oxygen Permeance
1 ppm Ethanol .

Oxygen Permeance
0 ppm Ethanol .

Oxygen Permeance
1 ppm Ethanol .

Oxygen Permeance
0 ppm Ethanol .

Oxygen Permeance
1 ppm Ethanol .

Oxygen Permeance
0 ppm Ethanol .

Oxygen Permeance
1 ppm Ethanol .

Oxygen Permeance
0 ppm Ethanol .

Oxygen Permeance
1 ppm Ethanol .

Oxygen Permeance
0 ppm Ethanol .

Oxygen Permeance
1 ppm Ethanol .

Oxygen Permeance
0 ppm Ethanol .

Oxygen Permeance
1 ppm Ethanol .

Data of

Data of

Data of

Data of

Data of

Data of

Data of

Data of

Data of

Data of

Data of

Data of

Data of

Data of

Data of

Data of

LDPE 1.5 mil

LDPE 1.5 mil

Cellulose Acetate

Cellulose Acetate

Polyvinyl Acetate

Polyvinyl Acetate

PVB 1

PVB

EVAc 0.8 mil

EVAc 0.8 mil

PVC

PP (0% Ceramic)

PP (0% Ceramic)

PP (3% Ceramic)

PP (3% Ceramic)

vii

0.9 mil

0.9 mil

1.4 mil

1.4 mil

Page

79

80

81

82‘

83

84

85

86

87

88

89

9O

91

92

93

94

LIST OF TABLES (CONTINUED)
Table Page

32. Oxygen Permeance Data of PP (7% Ceramic) 1.8 mil
0 ppm Ethano 1 O O O O O O O O O O O O O O O O O O O 9 5

33. Oxygen Permeance Data of PP (7% Ceramic) 1.8 mil
1 ppm Ethanol . . . . . . . . . . . . . . . . . . . 96

34. Oxygen Permeance Data of PP (3% Ceramic) 1.4 mil
0 ppm Ethanol (Tenax Pathway) . . . . . . . . . . . 97

35. Activaton Energy of Polymer Samples . . . . . . . . 99

viii

LIST OF FIGURES
Figure Page

1. Typical Dual-Mode Sorption Isotherm
and Its Components . . . . . . . . . . . . . . . . . 8

2. Flory- Huggins Sorption Isotherm
Nylon 6I/6T and Water Vapor . . . . . . . . . . . . 15

3. Modified Oxtran 100 Diagram . . . . . . . . . . . . 36
4. The Schemetic of Ethanol Vapor Generator System . . 38
5. Flow Diagram of Preconditioning System . . . . . . . 40

6. Flow Diagram of Preconditioning System 42

7. Oxygen Permeance of PP (3% Ceramic) . . . . . . . . 46

8. Oxygen Permeance of PP (3% Ceramic)
Tenax Pathway . . . . . . . . . . . . . . . . . . . 47

9. Ethanol Calibration Curve for the GC (1) . . . . . . 58
10. Ethanol Calibration Curve for the GC (2) . . . . . . 60
11. Equilibrium concentration of Ethanol . . . . . . . . 63

12. Schemetic of Diagram for Determining Ethanol
Absorption Capacity of Tenax . . . . . . . . . . . . 67

13. Ethanol Sorption Capacity of Tenax . . . . . . . . . 69

ix

INTRODUCTION

In the past, the production of packaging materials was based
exclusively on "natural" materials such as wood, cotton,
sand, and metal. However, synthetic polymeric materials
that were developed mainly after 1930, are now increasingly
playing an important role in the packaging industry. These
polymeric materials have some advantages and disadvantages
compared to other packaging materials. The advantages
include the versatility that these materials offer to the
packaging designer, light weight compared to glass and metal
packaging, and resistance to breakage. However, polymeric
packaging materials are semi-permeable and are therefore
able to interact with small molecules such as gases, water,
and organic vapors. Specifically, polymeric materials
exhibit physico-chemical interactions with small permeant

molecules based on sorption and diffusion mechanisms.

Polymer-permeant interactions have important practical
effects since polymeric packaging materials may change its
original properties during the shelflife of the package. It
is important therefore, to understand the mass transfer
behavior of the product-package system in order to better
apply a specific behavior of package/product system. This

1

2
behavior includes the sorption, diffusion, desorption, and
evaporation of the permeant molecules coming from the

product as well as from the external environment.

The use of polymeric packaging material for Modified
Atmosphere Packaging and Controlled Atmosphere Packaging
(MAP/CAP) of respiring foods -e.g., fresh produce - presents
a technical challenge to packaging and food technologists.
In the normal aerobic respiration of produce, oxygen is
consumed as carbohydrates are converted to carbon dioxide,
and water, to produce energy. One of the objectives of
MAP/CAP is to extend the shelflife of produce by reducing
the rate of respiration of the product, which reduces the
rate of substrate depletion, carbon dioxide production,
oxygen consumption and energy release (Zagory et a1. 1988).
The result of this controlled metabolism, is a potentially
longer shelflife.‘ The rate of respiration and the metabolic
pathway of respiration are subject to both internal and
external influences such as temperature and oxygen
concentration. The respiration rate can change during the

natural processes of ripening, maturity, and senescence.

The rate of respiration is sensitive to changes in oxygen
concentration below 8% and carbon dioxide above about 1%.
If oxygen concentration is reduced or carbon dioxide
concentration is elevated beyond the critical concentration

levels required by the product, the physiological activity

3
associated with anaerobic respiration will increase (Zagory
et a1. 1988). This anaerobic activity triggers several
chemical reactions that normally produce aldehydes,
alcohols, and other volatile chemicals (Kader, 1986). Once
the anaerobic process is developing the product will require
a more oxygenated environment. This will require a higher

value of the oxygen permeability of the packaging material.

Several alternatives may be considered in order to supply
adequate oxygen at the required time, ie., when the produce
goes from an anaerobic to an aerobic phase. One is to
develop biosensors to be used to indicate the anaerobic
condition, however, these biosensors have not been
successfully developed yet. The other alternative is the
removal or partial elimination of packaging material used
during the anaerobic condition after a pre-determined period

of time.

However, as mentioned earlier, organic volatile compounds
such as aldehydes and alcohols are generated during the
anaerobic phase of the package shelflife. since the mass
transport characteristics of permeants such as oxygen
through polymeric materials may be affected by the sorption
of organic vapor by the polymer, it is reasonable to
investigate, oxygen permeability changes due to the presence

of such volatile organic on selected polymeric samples. If

4
oxygen permeability of a given film is increased, by the
presence of organic vapors such as ethanol, it may be
possible to use the presence of volatile compounds produced
during the beginning of the anaerobic respiration, to

increase the flux of oxygen into the package.

Most of the permeability studies on polymeric packaging
material have been focused on determining the basic
permeability parameter, ie., sorption, diffusion, and
permeability coefficients of a single penetrant in mostly
pure or uncontaminated polymers. However, the study about
effects of organic vapors on the oxygen permeability of
polymer membrane is very limited. This project focuses on
describing the effect of ethanol which is the by-product
from anaerobic respiration on the oxygen permeability
properties of polymers. A major concern is the level of
ethanol concentration in the head-space that may affect the

oxygen permeability of the membrane.

The objective of this research was:

1. To develop a test apparatus to study the effect of
ethanol vapor on the oxygen permeability. This will
include a modification of an OXTRAN permeability tester.

2. To experimentally determine the effect of ethanol vapor
on the oxygen permeability of selected polymer films as a

function of ethanol vapor concentration.

LITERATURE REVIEW

DIFFUSION MODELS

In 1866, Graham postulated that the mechanism of the
permeation process included (a) sorption-solution of the
penetrant in the high concentration surface of the membrane,
(b) diffusion through the membrane by colloidal diffusion,
followed by, (c) desorption-evaporation from the downstream

membrane surface.

The sorption process can be explained phenomenologically as
the distribution of the penetrant between two or more phases
to include adsorption, absorption, incorporation into micro-

voids, cluster formation, solvation-shell formation and

other modes of mixing (Roger, 1985).

Penetrant molecules may experience more than one concurrent
or sequential mode of sorption in a given polymer material.
The distribution of penetrant between different modes of
sorption may change with changes in sorbed concentration,
temperature, swelling-induced structural states, time of

sorption to equilibrium, and other factors.

Most of the early studies on the permeation of molecules

5

6
through polymeric films were concerned mostly with rubbery
polymers. However, since plastic and glassy polymers are
produced in large quantity and are very popular in the
packaging industry, there has been a tremendous research
effort to try to describe the permeation phenomena of these
polymers. It was found that in all types of polymers , the
permeation mechanism through a homogenous membrane, in the
absence of gross defects involves sorption of penetrant in
the polymer, diffusion through the membrane followed by
evaporation from the surface into the ambient phase. The
diffusion of penetrants in the polymer membrane can be
portrayed as a sequence of unit diffusion steps or jumps.
This unit diffusion involves a cooperative rearrangement of
penetrant molecule and its surrounding polymer chain
segments. It is not necessary that, in the polymer
structure, an intrinsic hole exists in between two
successive penetrant positions. However, a certain number
of van der Waals type or other interactions between the
component molecule and chain segment must be broken to allow
a rearrangement of the local structure. Energy is required
for this rearrangement (or hole formation) against the
cohesive forces of the medium and effective movement of the

penetrant for a successful jump (Comyn, 1985).

In a polymer above its gas transition temperature, hole
density fluctuates as a result of thermal fluctuation.

Diffusion thus depends on the relative mobilities of

7
penetrant molecules and polymer chain segments as they are
affected by changes in size, shape, concentration component
interactions, temperature and other factors which affect
polymeric segmental mobility. The overall transport process
in a polymer therefore depends on polymer chain segmental
mobility and defect structures, such as void, microcracks
and other non-thermodynamic variations in polymer structure
and morphology. This includes spherulitic and lamellar
boundary regions in semi-crystalline polymers and permanent
or transient voids (excess free volume, frozen hole, etc.)

found in glassy polymer (Roger, 1985).

In 1879, Von Wroblewski showed that the solution of gases in
rubber followed Henry's law , Figure 1, Equation(1),
C ' RP (1)
C = Penetrant concentration in the polymer at
equilibrium.(cc(stp)/cc.polymer)
k a Bunsen solubility coefficient.
(cc.(stp)/cc.atm.)

Fixed gas pressure on the polymer.

'6
ll

Henry’s law simply states that the concentration of
penetrant in the polymer, C, is directly proportional to the

gas pressure or the concentration of gas, p, on the polymer.

Fick's first law is the fundamental law of diffusion (Comyn,
1985). It states that the flux, J, in the x-direction is

Concentration oi Dissolved Penetrant

 

 

 

Penetrant Pressure

Figure 1: Typical Dual-Mode Sorption isotherm
and its Component
(Stern and Trohalakl, 1990)

9

proportional to the concentration gradient (ac/6x)

J = - D aclax (2)

The diffusion coefficient, D (sq.cm/sec), may or may not be
independent of the concentration of gas in the membrane.
Diffusion behavior, in which D is only a function of
temperature and permeant concentration but not the time of

the permeation process, is called Fickian diffusion.

When Henry's Law is obeyed, the steady-state flux can be
expressed by combining the Henry's law and Fick’s law, the
relationship between permeability, diffusivity and gas

solubility becomes

1mg...
1 1
(3)
p -- kD (4)

J = Steady state permeation flux is the amount of substance
diffusing across unit area in unit time.

p - Pressure difference between top and bottom faces of the
membrane.

P - Steady state permeability which has typical units of

cc(stp)cm)/(sec.sqcm.atm.

10
An increase in temperature provides energy for a general
increase in segmental motion. The effect of an increase in

temperature may also be expressed in terms of the increase

in free volume (Roger, 1985).

For the frequently observed ideal behavior noted in organic
rubbers the diffusion coefficient varies with temperature by

an Arrhenius relationship:
D = Doexp(-E,/RT) (5)

1% = Pre-exponential factor
Eh==.Activation energy for diffusion (Cal)
R - Gas constant (Cal/degree.mole)

T - Absolute temperature (degree Kelvin)

Studies of transport of penetrants in glassy polymers
revealed that the sorption behavior in the polymer is more
complicated than that represented by Henry's Law. These
models include dual-sorption modes for permanent gas and the

extension of this model in the case of plasticized

penetrant-polymer system.

Dual Mode Sorption Models

W
The mechanisms of gas diffusion are different at

temperatures above and below the glass-transition

ll
temperature, T9, of the polymer, ie., when the polymers are
in their "rubbery" or ' glassy" state, respectively (Stern

et al. 1990).

Michael et a1. (1963) proposed a two-mode sorption model.

This model postulates that a gas dissolved in a glassy

polymer consists of two distinct molecular populations:
1. Molecules dissolved in the polymer by a mechanism

described by Henry’s Law, and
2. Molecules dissolved in a limited number of fixed,

pre-existing microcavities, or a fixed sites, in the
polymer matrix, described by the Langmuir equation

on.

The concentration of molecules dissolved by the simple
dissolution process, C4, .is related to the penetrant
equilibrium pressure, p, by a Henry's law isotherm as in
equation 1.

Cd " kP (1)

The concentration of molecules dissolved in microcavities,

C", is described by the Langmuir equation:

 

(5)

12
Where Ca' is a ”Langmuir Saturation” constant, and

b is a " Langmuir affinity constant

The total concentration of the dissolved penetrant C, at a
given p and temperature is then obtained from the linear
combination of the two populations and given by the sum of

equations (1) and (6).

ésbP
( 1 flap)

(7)

6%C5+C;ekp+

Typical dual-mode sorption isotherm and its compounds are

shown in Figure 1 (Stern et al., 1990).

The permeability coefficient, P, for gas transport across a

glassy polymer membrane is then given by the relation:

" (1+FK)
PekDy—IIEE—

(8)

(9)

(10)

DK and DD - mutual diffusion coefficients of the two
penetrant populations of concentration Oh and CD,

respectively.

The formulations of the sorption models presented assume
that the solubility of the penetrant gas in a polymer is
very low, and that consequently the polymer is not
plasticized to any significant extent by the penetrant.
However, for many penetrant-polymer system, D is not a
constant but rather is a function of concentration or in
some cases the elapsed time. The concentration dependence
is a consequence of the plasticising action of sorbed
penetrant and/or various mechanisms which localise a portion
of the sorbed penetrant. For example, the permeation of
gases with higher critical temperatures, such as organic
vapors and water vapor, exhibit sufficiently high
solubilities to plasticize glassy polymers which therefore
can not be described by using only the previous discussed

sorption models.

W
.In general, the diffusivities of penetrants that swell
glassy and rubbery polymers increase with concentration.

14
The sorption isotherms are normally well-described by the
Flory-Huggin equation instead of Henry's Law as shown for a

general case in Figure 2.

The isotherm represents a preference for penetrant-penetrant
pairs to be formed such that the solubility coefficient
increases continuously with pressure. There are two
principal physical interpretations of this behavior. One is
that the first molecules sorbed tend to loosen the polymer
structure locally and make it easier for subsequent
molecules to enter in the neighborhood of the first rather

than to go elsewhere.

This interpretation implies that the sorbed penetrant
effectively plasticises the polymer and the Flory-Huggin
isotherms are observed when a liquid or vapor penetrant is a
strong solvent or swelling agent for the polymer (Roger,

1985).

Another physical interpretation of this behavior is
represented by the systems in which the interactions among
penetrant are stronger than the interactions between polymer
and penetrant. As a result the stable sorption sites of
primary penetrant on the polymer will be the sites for the
sorption of consequent penetrants on the polymer.

Therefore, the sorption concentration increase with

increasing clustered molecules. However, in this behavior,

Volume Fraction of Water in Polymer

15

0.11

 

. 999
§§§§asa§8

 

0.01 -

 

 

 

0 0.10.20.30.40.50.60.70.80.91 1.1
Water-Activity

m2! How-Huggins Sorption IsouIerrn
Nyloamndwatervaporatfic

16
it would be expected that the diffusion coefficient would

decrease with increasing C (Roger, 1985).

MW

Hernandez et a1. (1992), had studied the effect of sorbed
water on the oxygen permeability of Nylon 6I/6T films. The
authors found that as water content in polymer increased,
the oxygen diffusion coefficient increased, and the
solubility of oxygen decreased. However, the decrease in
the oxygen solubility was more significant than the increase
of the diffusion coefficient. The authors proposed a dual
mode sorption model based on Langmuir and Flory-Huggins
mechanism. At water activities below 0.1, water
preferentially chemiabsorbs to amide bonds although only a
low mole fraction of the total hydrogen bonding sites on the
polymer are occupied. At higher water activities, the model
predicts that water molecules cluster among themselves.

This mechanism results in an increased capacity of polymer
to accommodate water molecules and therefore oxygen
permeability decreases. This study suggested that a
distribution of sites for each penetrant was present with in
the polymer matrix. The study also indicated that not only
is there competition for Langmuir sites, but the
availability of these sites depends on the type of molecules

and more specifically on the size of penetrant.

This phenomenon of size distribution of sorbed molecules

17
appears to take place also within other polymers and
sorbants. For example, Gedraitte et al [7] reported a size
distribution of additive sorption centers in polyethylene.
The authors found that the sorption of various additives by
high density and low density polyethylene such as hexane and

isopropanol obeyed the Langmuir sorption law.

These results, coupled with the availability of the model
described by the equation indicate, in principle, that the
permeability of oxygen should be affected by the presence of

organic molecules sorbed by a polymeric matrix.

PERMEABILITT MEASUREMENT

There are two test methods which provide quantitative
measurement for the rate of diffusion of gases or vapors
through polymer membranes: the isostatic method and the

quasi isostatic method.

In the first method, the test system allows for the
continuous collection of permeation data on vapor or gas
through a polymer membrane from the initial time zero to
steady-state condition, as a function of temperature and
permeant concentration. An example of equipment using this
method is OXTRAN 100 permeability tester which was used in
this study. The instrument consists of a measuring cell

divided into two sections by the film which will be tested.

18
The upper cell is the high oxygen concentration chamber,
oxygen will permeates through the tested film to the lower
chamber which then will be conveyed to the sensor by the
carrier gas. The sensor consists of an electro-chemical
cell made of nickel, cadmium and graphite that is immersed
in a basic electrolyte. Oxygen will react with cadmium
under high humidity and release electric current which then
will produce voltage when it is connected to a suitable
resistance and the voltage can be recorded. This value can
be converted to permeance value by multiplying with a

conversion factor.

In the second method the permeated gas is accumulated and
monitored as a function of time. Daynes in 1920 (2) showed
that, solubility coefficient, D is related to the time
required to achieve steady state permeation through an
initially degassed membrane (so-called " Diffusion lag

time", 0).

As shown in equation (11), the time lag is quantitatively
related to the diffusion coefficient and membrane

thickness,l, for the simple case where both k and D are

constants

(11)

19

PERMEATION OE MIXTURE.

Research involving the permeation process of organic vapor
has been mostly focused on single component organic
vapor/polymer systems (Rogers et al., 1960, Gilbert et al.,
1983, Niebergall et al., 1978., Zobel, 1982, Rogers,1964,
Baner et al., 1968, Hernandez et al., 1986, Mohney et al.,
1988, and Liu et al., 1986). These studies provided crucial
information about the permeation mechanism of organic

penetrants in polymer membranes.

Laine et a1. (1971), conducted a study on organic vapor
permeability of polyethylene film. The result revealed that
in polyethylene, which is nonpolar, the permeability is
lowest for polar components and highest for nonpolar

components.

A number of studies involving the permeation of mixed gas
have been conducted. One of the early studies was carried
out by Alexejev et al. (1927), who conducted studies on the
permeation of pure carbon dioxide, oxygen, acetylene,
nitrogen and air, and their mixtures in a wide variety of
compositions through rubber membranes. The study showed
that the permeation rate of gas mixture was equal to the sum
of the rates of its constituents. .Meyer et al. (1957),
'found no effect of one penetrant gas on another, however,

the time taken to establish the steady state increased when

20

gas mixtures were used.

The research of Pye et al. (1976), confirmed the previous
study which revealed that in the study system which involves
noninteractive materials, gases permeate independently of
each other even at very low partial pressures. Their
results are in agreement with those of Stannett et al.

(1957), Stern (1972) and Rogers (1965).

According to Pye et al., the permeability of a membrane to a
component A may be reduced due to the sorption of a second
component B in the polymer which therefore effectively
reduces the microvoid content of the film and the path for

the nonreactive gases.

Chern et al. (1983), conducted research in-"second
component" effects in sorption and permeation of gases in
glassy polymers, which revealed that the carbon dioxide flux
through Kapton polyimide was depressed by the presence of
water vapor. This study suggests that competition of mixed
penetrants for sorption sites an transport pathways
associated with unrelaxed volume in glassy polymers is a

general feature of gas/glassy polymer systems.

Lui et al. (1988), and Delassus et al. (1988), both found
that water vapor exhibited strong interactive effects with

moisture sensitive materials (EVAL and EVOH). This was due

21
to the plasticising effect of the sorbed water which
resulted in the increase of the permeability of the other
components. However, Landois-Garza et al. (1988), who
studied the permeation of PVOH film by ethyl esters,
postulated a trend toward lower permeability values as
relative humidity increased. This finding was contrary to
the work of Liu et al. (1988), and Delassus et al. (1988).
The authors explained that the decrease in permeability was
mainly a result of the lowering of the solubility as
relative humidity increased due to a competition effect
between the water molecules and the ethyl ester molecules.
The highly polar water molecules were able to compete more
effectively than the nonpolar ethyl ester molecules for

absorption sites of the also polar PVOH.

Hensley et al. (1991), conducted a study on the permeability
of binary organic vapor mixtures through polypropylene film.
The results showed that, independently, the organic vapors
showed concentration dependency for both permeation and
diffusion characteristics. For binary mixtures, the total
permeation rate of the mixture was much higher than that of

the pure components.

Sadler et al. conducted a research on ”Oxygen permeability
of low density polyethylenes as a function of limonene
absorption: An approach to modeling flavor scalping. The
study suggests that oxygen permebility might provide

22
information on volatile scalping. That is the increasing of
oxygen permeation would reflect absorption of volatiles, and

the desorption of volatile would reduce oxygen permeabilty.

Thalmann (1990), studied the sorption of solvents in
plastics and solvent desorption and retention. The solvents
included methanol, ethanol, n-propanol, and ethyl acetate.
Thalmann conducted the sorption experiments in the vapor
phase in a closed desiccator with special cover. The change
in weight was measured continuously as time increased.
Sufficient solvent was placed in the lower part of the
desiccator to ensure a vapor-saturated atmosphere. The
plastic samples were suspended on a microbalance. As soon
as the samples were fixed and the desiccator closed, the
weight registration started with an initial zero adjustment.
The sorption experiments were continued until they reached
an approximate equilibrium of saturation. The sorption of

each polymer is shown in Table 1.

The above review describes the permeability studies of
various conditions which reveal that permeability mechanism
of small molecules through polymer membranes depends on
penetrant-polymer interaction in both sorption state and
diffusion state. And this leads to the assumption that
the presence of organic molecules sorped by polymeric matrix
may affect oxygen permeability of a polymer. The trends of

such an effect is not yet confirmed which can involve either

23
organic molecules plasticizing a polymer as in the Flory-
Huggin model and results in higher oxygen permeability or
the competition between organic molecules and oxygen
molecules. This study is an attempt to clarify the above
assumption through measuring oxygen permeability of various

polymer films in the presence of a low concentration ethanol

vapor.
MODIEI- ATMOSP’E CONDITION

The specific optimum levels of O, and CO, have been studied
and reported by many researchers (Radar, 1980). Research on
packaging materials is important today because the final
package will have to allow enough 02 to pass through and
reach the product in order to eliminate the potential of
anaerobic condition. This should be done at such a rate
that the 02 concentration in the headspace is maintained at
a much lower level than atmospheric 0, which will result in
the desired quality maintenance. In addition, CO2
permeability should be such that enough C02 is vented out of
the package while the optimum level of C02 maintained
inside.

Although many plastic films are available for packaging
purposes, relatively few have been used to wrap fresh
produce. Even fewer have gas permeabilities that make them
suitable to use for MAP/CAP. Because 02 content in a

MAP/CAP is typically being reduced from an ambient 21% to

24
2-5% within the package, there is a danger that CO2 will
increase from ambient 0.03% to 16-19% in the package. This
is because normally, this is a one-to-one correspondence
between 02 consumed and C02 produced. Because this high
level of CO, would be injuriousto most fruit and
vegetables, an ideal film must let more CO, exit than it
lets O, enters. The CO, permeability should be somewhere in
the range of 3-5 times greater than the oxygen permeability.
The 01 and C02 permeabilities of films available for

packaging fresh produce are as shown in Table 2.

Table 1: Ethanol Sorption Test Data of Polymer Films
(Thalmann, 1990)

Film Temperature Weight increase
(’C) -------------------------
mg mg dm, %
LDPE 49.1 3.28 2.10 0.43
OPP 25 8.46 4.13 1.13
50 4.46 2.85 0.78
P8 26.1 32.57 20.84 3.63
50 35.36 22.63 4.02
Rigid PVC 25 19.12 12.24 2.35
50 42.91 27.46 5.34

25

Table 2: Permeabilities of Films Available for Packaging
Fresh Produce (Sagory et al., 1988)

Film Type Permeabilities
(cc./m2.mil.day.atm.)
’E;;;3;'SIS;I§; """"" 353;; """"

Polyethylene

Low Density 17,700-77,000 39,00-13,000
Polyvinyl

Chloride 4,263-8,138 620-2,248
Polypropylene 7,700-21,000 1,300-6,400
Polystyrene 10,000-26,000 2,600-7,700
Saran 52-150 8-26

Polyester 180-390 52-130

MATERIAL AND METHODS

MATERIALS

HelmeLEiims

PET (Mylar 50K 23) 0.7 mil (Du Pont Co., Chemicals &
Pigment Dept., Wilmington, DE)

Saranex 2.0 mil (Dow Chemical, Midland, MI)

LDPE 1.5 mil (unknown source)

Poly propylene (0% ceramic 0.9 mil, 3% ceramic 1.4 mil,
and 7% ceramic 1.8 mil provided by Kwang-Ho Lee of STC
Corporation, Kyoungki, Korea)

Poly vinylchloride 1.0 mil (Mobil Polymer US.Inc.,
Norwalk, CT)

Oriented Polystyrene 1.0 mil (unknown source)

Ethylene vinyl acetate co-polymer 0.8 mil (unknown source)
Cellulose acetate 0.8 mil (unknown source)

Polyvinyl acetate 1.0 mil (unknown source)

Poly vinyl butyral 1.0 mil

Poly (vinyl butyral) films (PVB) were casted from a

solution prepared by dissolving Poly(vinyl butyral) powder

which consisted of 19% hydroxyl/ 1% acetate / 80% butyral

(Scientific Polymer Products Inc., Ontario, NY) in absolute

ethanol until saturated. The saturated solution was extended

26

27
on a polyethylene film by using coating bar number 34. The
solvent was evaporated at room temperature for 24 hours and
then was put in a vacuum oven (set at 50°C) for 4 hours.
The poly(vinyl butyral) layer was easily removed from the
polyethylene film, the thickness was measured as 1.0 mil.
- Polyethyl acrylate
Prepared by coating a bleached kraft paper (4.2 mil) with
polyethylene acrylate 18% solution in toluene (Scientific
polymer products, Inc., Ontario, NY). A coating bar No. 34
was used for extending the polymer solution on the paper
surface. The coated material was left at room temperature,
under hood for 24 hours. It was dried in a vacuum oven set

at 50°C for 4 hours. The total thickness of the coated

material is 4.3 mil.

GAE

- Nitrogen gas
High purity dry nitrogen was provided by ASA Gas, Inc.
(Cleveland, OH)

- Carrier Gas
Nitrogen dry grade gas containing 1% Hydrogen, supplied by
ASA Specialty & Medical Gases Division (Maumee, OH)

- Permeant _
Oxygen supplied in the form 'of compressed air (02 partial
pressure equals 0.21 atm), obtained from ASA Gas, Inc.

(Cleveland, OH).

28
Chemicals
- 1, 2-dichlorobenzene
HPLC grade, Aldrich Chemical Co. Inc., (Milwaukee, WI)
- Ethyl Alcohol USP, Absolute - 200 proof, Midwest Grain Co.
of Illinois, (Pekin, IL).
1 - Tenax SC 35760 Mesh, Alltech Associated, Inc., (Deerfield,

IL).
nonsense or roam amass

1. Low-Density Polyethylene (LDPE)
This is a thermoplastic polymer produced by the
polymerization of ethylene gas. Its molecular structure of

this polymer can be represented as:
q_-[CH2]—s

The polymer is obtained from a non-catalytic high-pressure
process, therefore, it has a branched structure. The degree
of crystallinity in LDPE is a function of the amount of
short chain branching, normally in the range of 30% to 40%.
This polymer has good oil resistance because of the
non-polar structure and also is a good water barrier.
However, it is a poor barrier to most other gases. For
instance, the oxygen permeability coefficient is between
6,000-15,000 cc.mil/day.m’.atm. The glass transition

temperature is -120°C and PE is a polymer which sorbs large

29
amount of organic vapors. This is a inexpensive polymer

widely used in the packaging industry.

2. Ethylene-Vinyl Acetate copolymer (EVAc)
--rCH2-CH.-CH-CH.-cn.1--.

c
0 on,

Ethylene-vinyl acetate copolymers include a board range of
thermoplastic material with vinyl acetate constants from
below 5 to 50% incorporation. Compared to other polyolefins
such as LDPE, EVAc is more polar and less crystalline. As
the vinyl acetate (VA) content increases the low-temperature
flexibility and impact resistant increases but the barrier

properties decreases. Above 50% VA incorporation, EVAc is

totally amorphous.
3. Polyvinyl Chloride (PVC)
-- [CHz-CHCI ] --_

This polymer has atactic stereochemical configuration,
therefore, it is amorphous. However, because of the
polarity of the chloride groups is high, the polymer chains
are tightly packed (Tgs 87°C). Stabilizer are always added

to stabilize PVC since it tends to degrade at high

30
temperature. The barrier properties depends on how much it
is plasticized, usually, oxygen barrier is low. PVC has

excellent clarity, and is among the lowest priced film.

4. Vinylidene Chloride Copolymer

Saran is a copolymer of Vinylidene chloride (VDC) with vinyl
chloride, acrylates, or nitriles. The choice of comonomer
significantly affects the properties of the resulting
polymer. The important attributes of copolymers are their
low permeability to gases and liquids and also high chemical
resistance. Saran is used in food packaging as barrier to

moisture, flavorants, and odors.

5. Polypropylene (PP)

"[CHrCHJ".
CH:

The most common commercial form of PP is isotactic PP which
allows crystal formation (60% crystallinity). The I
crystalline nature gives it good solvent and heat
resistance. The T9 of PP is about 10°C which is higher than
PE because of the large methyl substituent group. Oxygen
permeability is about 2 ,400-4,000 cc.mil/m’.day.atm. PP has
good clarity, its high melting point makes it suitable for
heat-processed product, and it is among the lowest-priced
transparent film. The ceramic filled PP is developed in

Korea and was kindly obtained from Dr. K Yam of Rutgers

31

University

7. Polystyrene (PS)

-- [CH-CHI] --s

Crystal P8 is an amorphous polymer made from the addition
polymerization of styrene monomer. The T9 of PS is
relatively high (about 90°C). This is because the phenylene
group, though it is not polar, is bulky which prohibits
chain mobility. It has good optical properties. The high
moisture and gas transmission rates are very desirable for

fresh produce and baked goods.

8. Polyethylene terephthalate (PET)
This polymer is a condensation polymer generally between
ethylene glycol and terephthalic acid with the structure as
below:

--rc- -c-o-CH.-cnz-01--.

O O

The ring structure of the back-bone chain provides the
rigidity of this polymer. Thus it exhibits a high
transition temperature (Tg - 73—80°C, Tm - 246-265°C).
Carbonyl groups provide high molecular force, therefore, it

exhibits high barrier properties. The oxygen permeability

32
is about 50-100 cc.mil/day.m2.atm. It also has good
chemical resistance and good transparency. Its cost is

rather high.

9. Cellulose Acetate

Cellulose Acetate is an acetic acid ester of cellulose.

The moisture sensitivity is less than that of Cellophane.
It is nearly always used plain, without a heat-seal coating
plasticizers are frequently added to improve its impact
strength. Moisture and gas barrier of this material are

poor (oxygen permeability coefficient is about 1000-3000

cc.mil/sqm.day.atm.).

10. Polyvinyl Acetate

-" [CHz-CH] --s
O'C'CH3
O

This polymer is amorphous because of atactic stereochemical
configuration. Tg of this polymer is about 28-31°C. This
polymer is soluble in organic solvent, eg. esters, ketones
etc., but it is insoluble in the lower alcohol (excluding

methanol), water and nonpolar liquid such as ether.

11. Polyethyl Acrylate
Polyethyl acrylate is an acrylate ester which is an
unsymmetrically substituted ethylene. This polymer is a

33

rubberlike, soft and extensible polymer with Tg = -24°C.

12. Polyvinyl Butyral (PVB)

Polyvinyl butyral is a member of the polyvinyl acetal
family, made by reacting polyvinyl alcohol with
butyraldehyde, with some unreactive PVA groups retained in

the polymer. It is soluble in alcohol and the structure is

shown below:

-- [CH2-CH-CH2-CHJ --n
C O
CH
CH,
ca,
CH:

METHODOLOGY

The oxygen permeance of the film samples was determined in
accordance with ASTM Standard D 3985-81 "Oxygen Gas
Transmission Rate Through Plastic Film and Sheeting Using A
Coulometric Sensor". The studies were carried out on an
Oxtran 100 Permeability tester (Modern Controls, Inc., Elk
River, MN), whose operation is based on the isostatic
method. Since the oxygen sensor of the Oxtran can be
damaged by high concentration of oxygen, the surface area of
high oxygen permeance film had to be reduced. This was
achieved by utilizing a impermeable mask that reduced the

exposed area of the film by a factor of 10.

34
The Oxtran 100 oxygen permeability tester was modified to
prevent the ethanol vapor used during permeability tests
from being conveyed by the carrier gas to the coulometer
sensor. By preventing the ethanol vapor from contact with
the oxygen sensor, potential damage of the sensor was
avoided. Possible effects of the presence of ethanol vapor
in the sensor could be damage to the sensor or interference

with the permeability output.

A trapping agent was used to retain the ethanol vapor in the
carrier gas and was placed after the permeability cell and
before the sensor. The trapping agent must have a known
ethanol sorption capacity and it must not absorb oxygen gas.
Tenax was the trapping agent selected, and the following
tests were performed:

1. Determination of oxygen absorptivity of tenax.

2. Determination of ethanol sorption capacity of

tenax.

These tests are described in Appendix 3 and Appendix 4,

respectively.

Results of the oxygen absorptivity test indicated that tenax
does not retain oxygen. The ethanol absorption capacity of
tenax was determined to be 657 pg ethanol/g of tenax at 6
ml/min of flow. However, the absorption capacity might be
changed as a function of the flow rate of ethanol stream.

Calculation for amount of tenax necessary for each ethanol

35

concentration is presented Appendix 5.

The Oxtran apparatus was modified by connecting a glass tube
containing the tenax to the "Package Test Fitting” -
connection as indicated in Figure 3. In this way, tenax
was able to trap ethanol vapor from the carrier gas which

conveyed the oxygen permeated in the presence of ethanol

vapor before going to the sensor.

The concentrations of ethanol vapor used in this study were
based on studies conducted by Dr. A. Cameron (Horticulture
Department, Michigan State university) on fresh fruits. The
value of the ethanol vapor concentrations tested in this
study corresponded to the head-space equilibrium vapor
concentration of a ethanol in water 100 ppm (volume/volume).
The determination of equilibrium head-space ethanol vapor
concentration of the ethanol/water solution is described in
Appendix 2, which reveals that for a solution of 100 ppm
Ethanol in water, a concentration of ethanol in headspace
equal to about 1 ppm (weight/volume) is obtained. In this
study, the oxygen permeability through the films was
determined in the presence of 1 and 7 ppm ethanol vapor
(wwt/V). The ethanol vapor concentration are expressed
through out in ppm (mass/volume), vapor in gas (nitrogen or
air), where 1 ppm equal 1 pg ethanol per cm3 of gas mixture,
at 1 atm at 21 °C. Prior to each permeability test, the

tested film sample was mounted in the permeability cell,

36

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37
both surfaces of the sample were preconditioned by being
exposed to ethanol vapor stream for about 24 hours. During
the permeability tests, air with adjusted ethanol vapor
concentration was flowed through the upper chamber of the
permeability cell throughout the test.

The gas streams containing the ethanol vapor were generated
by using an ethanol generator apparatus. The required
concentration was obtained by blending a stream of pure gas
with another gas stream of the same gas that bubbled in
chemically pure liquid ethanol. A controlled flow of pure
gas (nitrogen or air) was bubbled through pure liquid
ethanol in a gas-washing bottle to generate a mixture of gas
and ethanol vapor. To adjust the required ethanol vapor
concentration stream, a fraction of this gas mixture was
vented out to decrease the excessive flow and the rest was
mixed by the pure gas and adjusted to the required value.
The flow of gas streams was measured by flow meters and
could be adjusted by needle valves. Ethanol concentration
of the gas stream was monitored by withdrawing a sample from
the sampling port and injecting the sample into the SC. The
ethanol calibration curve of the SC is as shown in Appendix

1. The schematic of the ethanol generator is as in

Figure 4.

The experimental method to measure the effect of ethanol on

oxygen permeability of the film samples is as follows.

3'8

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39
The test was conducted to determine the conversion
factor which was used in calculating the permeance.
(The procedure is as shown in Appendix 6.)
Before conducting the permeability test, the tenax
system was prepared by eliminating oxygen from the
system. This was done by flowing the carrier gas (1%
hydrogen balance nitrogen) through the system until
zero steady baseline was obtained. The system was
thoroughly checked for leakage and was kept closed to
maintain its conditions.
Free-ethanol permeability measurement was conducted by
the conventional procedure and bypassing tenax system.
For oxygen permeability measurements in the presence
of ethanol, the tested film was preconditioned in the
ethanol vapor stream for 24 hours. This
preconditioning was carried out by passing the
required ethanol vapor stream into both sides of
permeability cell on which tested film was mounted.
This was achieved by connecting the ethanol vapor
generator, in which nitrogen was used as the pure gas,
at the carrier gas inlet of the Oxtran. The final
flow was adjusted to about 16 ml/min. The Oxtran was
set at bypass sensor, therefore, both surfaces of the
sample would be exposed by ethanol at adjusted
concentration (the flow diagram is as in Figure 5).
The oxygen permeability test was conducted in the

presence of ethanol by using an air-ethanol mixture as

40

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seam—m

 

 

 

 

 

 

 

 

 

 

 

41
a permeant vapor. This was obtained by connecting the
ethanol generator system, using air as the pure gas, to
the oxygen inlet of the Oxtran (the schematic is as in
Figure 6), the final flow was adjusted to about 16
ml/min. With this setting, ethanol vapor in air flowed
through the upper chamber. The permeability test was
then conducted in the conventional procedure, except
that the tenax system was used.
The output from the recorder which is in voltage units
was converted to permeance units that are in
cc/day.m2.atm. by multiplying the volt response times
the conversion factor (from Appendix 6) and dividing by
the partial pressure of oxygen in air. The equation is

as follows;

permeance=£1_tgg_eResponsex15 . 53 x10
0.21

The above experimental method was applied to both 1 ppm
and 7 ppm concentration levels of ethanol in the
permeation stream, except that a different amount of
tenax was used in each case. However, in the case of 7
ppm ethanol concentration, an excessive drop of
pressure through the tenax system was experienced.

This was a result of the large amount of tenax needed

(8 g). The problem was avoided by loosely packing

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42

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

43
the tenax in a cylinder, layers of tenax powder were
alternated with layers of glass wool. This provided an
acceptable drop in pressure. However, to protect the
coulometric sensor, only steady state transmission was
recorded.
The estimated percent error of each test was calculated
by calculating the percent deviation from three
permeability tests of a selected LDPE film sample as

shown in Appendix 8.

RESULT AND DISCUSSION

In this study, the effect of ethanol vapor on the oxygen
permeability of selected polymeric film was evaluated under
different ethanol vapor concentration values. To carry out
this study, an Oxtran 100 oxygen permeability tester was
modified to use a trapping agent to retain ethanol vapor
before reaching the oxygen sensor. Preliminary experiment
have shown that tenax, the trapping agent, does not absorb
oxygen, thus, producing no interference with oxygen
measurements. Ethanol vapor which was presented in the
permeability cell during the permeability test was trapped
by the tenax from the carrier gas stream, leaving the
carrier gas to convey the permeated oxygen to the coulometer
sensor. The tests were conducted at dry condition (0%
relative humidity) to avoid any effect of the water molecule
on the polymer and the tenax. In this study, the equipment

was designed for low ethanol concentration (below 20 ppm).

The oxygen permeability under three different ethanol vapor
concentrations (ie., 0, 1, and 7 ppm, weight/volume) were
measured. The experimental data for each polymer under
ethanol concentrations of 0 ppm and 1 ppm are presented in

Tables 9 to 32 (see Appendix 7). The graph comparing oxygen

44

45

permeance of both ethanol conditions of PP (3% ceramic) film
is shown in Figures 7 which reveal that the experiments
conducted under 1 ppm ethanol conditions required longer
time to establish steady state as compared to those of 0 ppm
ethanol vapor conditions. This due to the fact that the
connection of tenax to the Oxtran not only increased the
pathway between permeation cell to the sensor but also

resisted the flow of the gas stream.

To determine the effect of the pathway on the time to
establish steady state, oxygen permeability under 0 ppm
ethanol vapor and 1 ppm ethanol vapor conditions of
polypropylene (3% ceramic) were determined by using tenax
system. The respective graphs of permeance value versus
time are presented in Figure 8. This permeance profile was
compared to that in Figure 7 which was the permeance profile
of the same polymer under 0 ppm and 1 ppm ethanol conducted
by using a different pathway. The profiles reveal that by
using the same pathway, the time to establish the steady
state permeance of 0 ppm ethanol was increased compared to
that of non-tenax system. Therefore, the time to establish
steady state can be compared by modified Oxtran by using the
same pathway, however, in this study only steady state

permeability will be considered.

Due to fluctuations in room temperature, the permeability of

each condition was conducted under slightly different

Oxygen Permeance (ccim2.day.oim.)

 

46

 

 

—I— 0 ppm Ethanol

—e-— I ppm Ethanol

 

 

 

. L .L 4 A. L 4 L L
60 so 100
T'Ine(m'n.)

Figure 7: Oxygen Permeance of PP 3 % Ceramic 1.4 mil
at 23 C for 0 and 1 ppm Ethanol Condition

Oxygen Permeance(cclm2.day.atm)

‘47

 

 

 

 

 

 

120

Time (min)

Figure 8: Oxygen Permeance of PP
(3% Ceramic), Tenax Pathway

48
temperature values. To compare the steady state permeance
values among the different ethanol conditions and polymer
films, values of steady state permeance were normalized at

24 °C based on the Arrhenius equation;

(1'-T)
Ifi=$3expi§§—T%:i3—l

where, E = Activation Energy of polymer(cal/mole)
R = Sas constant = 1.98 (cal/Kelvin.mole)
T“.13 = Absolute temperature 1 and 2 (Kelvin)
P“ 15 = Oxygen permeance at absolute
temperature 1 and 2, respectively

(cc./sqm.day.atm.)

Normalized oxygen permeance values are as shown in Table 5
which shows only small difference of oxygen permeation for
the film samples, between the 1 ppm ethanol and non-ethanol
condition within 24 hours period. The percent difference is

in range of -13 to 2 percent.

For the case of 7 ppm, only the steady state was considered
in this test to avoid excessive exposure of ethanol to the
sensor, the results are shown in Table 4. The steady state

permeance values shown in Table 4 were also normalized to

49

values at 24 °C as presented in Table 5, these values show a
more significant effect of ethanol on the oxygen permeance
at 7 ppm ethanol conditions. In the case of PET, although
in the first experiment the oxygen permeance at 7 ppm
ethanol vapor concentration showed a significant increase, a
second experiment indicated only 5% difference between 1 ppm
and 7 ppm ethanol condition. Therefore, the effect of 7 ppm
ethanol vapor on the oxygen permeability in PET films is not
conclusive and further studies are necessary to confirm any

effect.

50

Table 3: Oxygen Permeance of Polymer Film Samples at 0 ppm
and 1 ppm (wt/vol) Ethanol Vapor (0% RH)

Film Thickness 0 ppm EtOH 1 ppm Eton
(mil, ------------------- -------- -------------
T(°C) Permeance T(°C) Permeance
(cc/m2.day.atm) (cc/m2.day.atm)
PET 0.7 24 22 24 19
Saran 2.0 24 10 24 10
LDPE 1.5 23 4500 24 4700
PVC 1.0 24 7500 24 7300
P8 1.0 23 4100 24 3800
EVA 0.8 24 10900 ‘ 24 11000
Cellulose 1.0 24 2600 24 2500
Acetate
PVA 1.0 26 860 24 800
Polyvinyl 1.0 23 3100 22 2700
Butyral
PP 0.9 23 4500 23 4300
0%Ceramic
PP 1.4 23 4500 23 4600
3%Ceramic
PP 1.8 21 2200 23 2200

7%Ceramic

51

Table 4: Oxygen Permeance of Polymer Film Samples at 0 ppm
and 7 ppm (wt/vol) Ethanol Vapor (0% RH)

Film Thickness Without EtOH With EtOH
(mil) T(°C) Permeance T(°C) Permeance
(cc/m2. day.atm) (cc/m2. day.atm)
PET 0.7 22 16 24 27
23 20 23 21
Saranex 2.0 24 10 22 8
LDPE 1.5 23 4500 22 4200
PVC 1.0 24 7500 22 6900
P8 1.0 23 4100 24 3800
EVA 0.8 24 10900 22 10000
Cellulose1.0 24 2600 23 1900
Acetate
PVA 1.0 26 860 23 .590
Polyvinyl 1.0 23 3100 22 2500
Butyral
PP 0.9 23 4500 22 4100
0%Ceramic -
PP 1.4 22 3700 22 3700
3%Ceramic
PP 1.7 21 2200 23 2100
7%Ceramic
Polyethyl 4.2 23 54E05 22 53E05
Acrylate

coated on paper

52

Table 5: Normalized Values of Oxygen Permeance of Polymer
Films at 24 °c (Calculated by using Arrhenius
Equation)
Film Steady state permeance
cc/m2.day.atm) APermeancet
------------ ----------------------------- of 7 ppm
0 ppm EtOH 1 ppm Eton 7 ppm EtOH (%)
PET 22 19 - -
18 - 27 50
21 22 5
Saranex 10 10 10 0
LDPE 4600 4700 4700 0
PVC 7200 7000 7800 8
EVA 10900 10800 10900 0
Cellulose 2500 2500 2000 -20
Acetate
PVA 760 800 640 -16
Polyvinyl 3200 3000 2800 -13
Butyral
PP 4700 4600 4600 0
0% Ceramic
PP 4800 4800 - -
3% Ceramic 4100 - 4100 -15
PP 2600 2400 2300 -12
7%Ceramic

* Based on oxygen permeance of 0 ppm

ethanol condition.

CONCLUSIONS

An apparatus was designed and built to test the effect
of organic vapors on the permeability and diffusion,
coefficient of oxygen. The same approach can be

employed for other gases such as carbon dioxide.

There was no significant effect of ethanol vapor in the
concentration range of 0-1 ppm (weight/volume) on the
oxygen permeability of selected polymeric film within a
24 hour period. However, the effect of ethanol vapor
at concentration higher that 1 ppm still need a further

study.

53

BIBLIOGRAPHY

BIBLIOGRAPHY

Baer, E. (1964). Engineering Qesign of Plastics. Polymer

science and engineering series., Reinhold publishing corp.
New York.

Brandrup, J., and Immergut, E.H., editor. (1975). Egiyng;
finngnggk, 2nd ed., A Wiley-interscience.

Chern, R.T., Koros, W.I., Senders, E.S., and Yui, R. (1988).
"Second component" effects in sorption and permeation of
gases in glassy polymers. Journal of embra e sc'enc ,
15:157 (1983).

Comyn, J. (1985) Pgiyne: Permeability, Elsevier Applied

Science Publishers, New York.

Delassus, P.T., Strandburg, S., and Howell, B.A. (1988).
Flavor and aroma permeation in barrier film: the effects of
high temperature and high humidity. Ianpi Jgugnai, Nov.

pp. 177.

Sedraitite, S.B., Marin, A.P., and Shlyapnikov, Y.A. (1989).
The Size distribution of additive sorption centers in

polyethylene. En, Egiyng: J., 25:31-41.

Hanlon, J.F. (1984). nnndngok of Packaging Enginegzing (2nd
ed.). Mc Sraw-Hill, Inc.

Hensley, T. M. (1991). The Permeability of Binary Organic
Vapor Mixtures through a biaxially oriented polypropylene

film. n.8, Thesis. Michigan State University, E. Lansing,
MI.

Hopfenberg, H.B., and Stennett, V. The Diffusion and
Sorption of Gases and Vapours in Glassy Polymers. The

physics 9: glassy polyners., pp.504-547.

Encyclopedia of polymer science and engineering (2nd.ed.),
Herman, F.M. et al., editor,(John Wiley & Sons,1989).

Hernandez, R.J., Saicin, J.R., and Srulke, B.A. (1992). The
Sorption of Water Vapor by an Amorphous Polyamide. angngi

9f_nembrane_§sisnse- 65:187-199

54

55

Huang, R.Y.M., and Lin, V.J.C. (1968). Separation of liquid
mixtures by using polymer membranes. I. Permeation of binary
organic liquid mixtures through polyethylene. lgnznn1_n1

Applied_2912mer_§ciense1. 12:2615-

Laine, R. , and Osburn, J.O. (1971). Permeability of

Polyethylene Film to Organic Vapor. gournai 9f Angling
Polxmer_§ciencei. 15:327.

Landois-Sarza, J., and Hotchkiss, J.H. (1988). Permeation of
High-Barrier Films of Ethyl Esters. Eggg_gng_pggkgging
intgzgggign, ASC symposium series 356. Hotchkiss,J.S.,
editor., American Chemical Society, Washington, DC.

Lui, R.J., Saicin,J.R., and Hernandez, R.J. (1988). The
effect of relative humidity on the permeability of toluene
vapour through a multi-layer coextruded film containing

hydrophilic layers. Packaging Technology nng Sgiengg,1:57-
65.

Pye, D.S., Hoehn, H.H., and Panar, M. (1976). Measurement
of Gas Permeability of Polymers. II Apparatus for
determination of permeabilities of mixed gases and vapors.

19urn_l_9f_Annli_d_Pglxmer_§sienss 20: 287.

Roger, C.E., Stannett, V., and Szwarc, M. (1960). The
Sorption, Diffusion, and Permeation of Organic Vapors in

Polyethylene. fignzngi g: Eoiyner Sgiengg,, 45;61.

Stennett, V., et al.,"Recent Advances in Membrane Science
and Technology", pp 69-121.

Stern, S.A., and Trohalaki, S. (1990). Fundamentals of Gas
diffusion in Rubbery and Glassy Polymers. fig;;ig;_zgiyngz§
ang_§;;ng;n;§§, Koros, W.J.,editor, ASC symposium series

424, pp. 22-59, American Chemical Society, Washington, DC.

Thalmann, W.R. (1991). Sorption of Solvents in Plastics and

Solvent Desorption and Retention. 2ngknging_1§gnngiggy_nng
Science. 3:67-82-

Zagory, D. and Kader, A. (1988). Modified Atmosphere

Packaging of Fresh Produce. Eggg_1ggnnglggy, September,
pp 70-77.

APPENDICES

56

Appendix 1

Ethanol Calibration Curve for Gas Chromatography
IDSLIBEEELI Hewlett Packard 5890A Gas Chromatography
Column - Supelco Wax 10
Cabowax 20 M

Condition

Oven temperature 80 °C
- Initial temperature 80 °C
- Initial time 1 minute
- Rate 4 degree/min.
- Final time 0
- Final temp 150 °C
- Flow 27.1
- Range 3
- ATT 0
Bgnggn;; 1. 1,2-dich1orobenzene maximum impurities and
specifications 98%, EM Science, Sibbstown, NJ.
2. Ethyl Alcohol USP absolute 200 Proof, Midwest
Srain Co., IL.
Density 0.7836 gm/ml at 21 °C.
Pzggggnxe; 1. Prepared standard ethyl alcohol solution at
various concentration (ie. 4 ppm, 10 ppm,
20 ppm, 40 ppm, 60 ppm, 80 ppm, and 100 ppm
(volume/volume)) by using
1, 2- dichlorobenzene as the solvent.

2. Inject .5 ul of prepared solution into the

57
SC. (The retention time of ethyl alcohol is
about 1.68 minutes.)
3. Plotted graph between quantity of ethanol

injected versus area response.

Result...

Table 6: Ethanol Calibration Data for Gas

Chromatography(1)

ESQETSE""§SI;;;'SE """"" 533212;"; """"" 2322;; """
ethanol ethanol injected ethanol injected area response
(ppm.V/V) *109(ml) *109(g) (area unit)

0 0.0 0 0 0

4 2.0 1.6 1101

10 5.0 3.9 2785

20 10.0 7.8 4174

40 20.0 15.7 7628

60 30.0 23.5 14034

80 40.0 31.3 15112

100 50.0 39.2 23423

Standard curve of quantity of ethanol injected versus area

response is as shown in Figure 9.

The linear relationship

between quantity of ethanol injected and area response is as

equation

-27.16 + $56.70 X

Neeflesponseim)

58

 

30°00 ' = -27.162+556.70x Fl“2=0.978

 

 

 

 

0 5 ‘ 10 A 15 20 A 25 30 as
Qt. of Ethanol Injected x E9 (9)
Figure 9: Ethanol Calibration Curve for the GC (1)

59

Table 7: Ethanol Calibration Data for Gas

Chromatography(Z)

23;;TSE""$SI£;;'SE """"" 632321;; """"" £322.31?"
ethanol ethanol injected ethanol injected area response
(ppm.V/V) *10’(ml) *109(g) (area unit)

0 0 0.0 0

4 2 1.6 1401

10 5 306 3471

20 10 7.8 5879

60 30 23.5 20792

100 50 39.2 37588

Graph plotted between quantity of ethanol injected and area
response is as shown in Figure 10. The linear relationship
is as equation:

Y = - 547.5 + 952.8 X

NeeReaponaetAU)

15000

10000

60

 

 

y: -472.26+950.65x 94230397

L A l 4 l a J. a l L L g L

 

s 10 1s 20 25 30 35
Qt. of Ethanol Injected x E9 (9)

figure 10: Ethanol Calibration Curve tor the GC (2)

 

61
Appendix 2

Determination of Equilibrium Concentration of Ethanol in the
Head-Space
Exggggnzgi 1. Prepared aqueous solution of different
concentration of ethanol (0.05%, 0.075%, 0.1%
0.125%, 0.50%, and 1.0%) by using distilled
water and placed in septa seal vial.
2. Kept this solution in room temperature for 2
weeks.
3. Injected 100 ul of the headspace of each
solution into the SC.
4. Calculated concentration of ethanol in
head-space using standard curve (Figure 20.)

Y = - 27.16 + 556.70 110'9 x

62

Besnit. Table 8: Equilibrium Concentration of Ethanol in

the Head-Space at 21 °C

Conc. of etOH Area response Quantity inj. Conc. of in

sample ( %byVol) (Area Unit) *109 (g) head-space
(Hg-lmll
0.051 _-----;Z;; --------- 70" .079
0.075 6162 11.1 .111
0.100 7561 13 6 .136
0.126 9792 17.6 .176
0.500 41564 74.7 .747
1.000 78934 141.8 1.418

Graph plotted between equilibrium concentration of ethanol
in headspace versus concentration of ethanol solution is as
shown in Figure 11. The linear relationship is as equation:

Y = 3.760E-03 + 1.427X

Conch head ewquolml]

63.

20

 

y .434190-3 +1.4266x 1102:0999

 

 

 

 

l L I 4 A; J A L l A A M k A i
00

00 02 0A OB OS 10
CWBJNEMUDW%DVVUJ

figure 11: Equilibrium Concentation of Ethanol
in the Headspace

64

Appendix 3

Oxygen Absorptivity of Tenax

Instznngnt; - Mocon Oxtran 100 Permeability Tester

- Linseis L6512 recorder.

Material; Standard reference Material 1470 Polyester film

for

gas transition from US Department of Commerce

National Bureau of Standards, Washington, D.C.

Permeance = 69.104 cc/m’.day.atm.

Egocgdure: 1.

Result:
Condition

With tenax

Calibrate the Oxtran 100 by using standard
Reference Material 1470.

Connect the tenax at the package test
fittings as the schemetic in Figure 3, tenax
was connected before the stream of carrier
gas go to the sensor, measure the
permeability of standard film again.

The condition which was used in this test is
dry condition at room temperature.

Compare the permeability of the standard film
by using the system with tenax and without

tenax.

Permeability output (mV)

5.1

Without tenax 5.1

65
From the result reveal that at dry condition, room
temperature, if tenax does absorb oxygen, it does not affect

the final reading.

66

Appendix 4

Ethanol Sorption Capacity of Tenax

Instrument;

Hewlett Packard 5890A Gas Chromatography

Column - Supelco Wax 10, Cabowax 20M

Condition - The same as in Appendix 1

(Schematic of the system is as in Figure 12.)

1.

Close the tenax system, adjust the
concentration until close to 1 ug/ml. The
concentration is determined by withdrawing
500 #1- gas from sampling port 1 by using
a gas-tight-syringe and inject the
sampling gas into the GC.

After get the desire ethanol
concentration, then open the needle valve
to let the ethanol vapor pass through the
tenax.

Sampling the gas from sampling port 2.
Determine the concentration until get the

consistent concentration.

6.7

. xece... we xtueaeo 5.99.6”
.9350 assesses: Low sagas: mo 03.6.5.3” .m— 0.50...

Loeeezeo .69; .9393”.—

E _

IAL- __

a «Lee M w
Flats“ cone-9.6)

t.

2 -

1
I
I
l
I
I
I
I
I
l
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

I
I
_-_..l

 

 

t...

 

m «use
Passe“ recap

 

 

r----------->-----------_-
fit?

 

 

 

 

 

68

Result Table 9: Ethanol Sorption Capacity Data of Tenax at

21 °C
Time Sampling Port 1 Sampling Port 2 Conc. of etOH
(min.) Area Response(AU) Area Response(AU) in port 2

(uglmll

3 - 332 .00079
8 - 378 .00079
12 589310 - -
18 - 314 .00066
24 597460 - -
29 - 333 .00069
36 - 274 .00058
41 575940 - -
46 - 319 .00067
53 - 379 .00079
62 - 328 .00067
69 - 3128 .000660
73 - 83799 .18858
77 - 469240 .985
82 - 569310 1.20
87 586510 - -
93 - 600770 1.26
106 564750 - -
118 - 610710 1.28

Graph plotted between concentration of ethanol in the
sampling port 2 (pg/ml) versus time (min) is presented in

Figure 13.

From the test result obtained, the average original
concentration of ethanol (concentration of ethanol in
sampling port 1) before the tenax is 1.2 ug/ml a with
standard deviation .02 ug/ml. The time before the ethanol
concentration in sampling port 2 started increasing was

about 60 minutes.

Concentration at man...)

69

 

 

 

 

 

 

1.5
*1 3 4|

1.0 - .
0.5 -

II Samplingportl

0 Sampling :1th ,

A. A1 A.A LL- I. A A I- . I l

0.00 A LA 20 40 so so 100

Tana (mire)

figure 13: Ethanol Sorption Capacity of Tenax

120

70
Gas flow in the tenax system was equal to 5.84 ml/min of
gas. Total amount of tenax was about 0.64 9. Therefore,
total amount of ethanol absorbed in the tenax at saturation
was, W. = 5.84 ml/min * 60min * 1.2 pg/ml = 420.48 pg.
Absorption capacity = A, = W../0.64 g.tenax.

= 657 pg.ethanol/g.tenax.

71

Appendix 5

Calculation for Amount of Tenax for Each Ethanol Concentration

From Appendix 4, the estimated capacity of tenax is equal to

657 pg ethanol/g tenax. The calculation for each

concentration is as follows;

1.2 ppn Ethanol,

Gas flow rate to the sensor is about 10 ml/min.

Estimated duration of test is about 120 mins.

Estimated amount of ethanol which would flow through tenax

through out the test, Wé== 10 ml/min * 120 min * 1.2 pg/ml
we = 1440 pg

Therefore, the least amount of tenax should be.used is

wT 1400 pg* 9 of tenax / 657 pg
WT = 2.2 g tenax.
In the permeability test amount of tenax used is 2.4 g
2 ppm Ethanol;
Gas flow rate to the sensor is about 10 ml/min.
Estimated duration of test is about 120 mins.
Estimated amount of ethanol which would flow through tenax

through out the test, WE== 10 ml/min * 120 min * 7 pg/ml.

WP.

8400 pg.

72
'Iherefore, the least amount of tenax should be used is

W, 8400 pg‘* g of tenax / 657 pg

WT = 13 g tenax.
In the permeability test only 8 g of tenax was used because
too much amount of tenax will prohibit the flow. Therefore,
for 7 ppm ethanol, only steady state transmission was

measured.

73

Appendix 6

Determination of the Conversion Factor for the Oxtran

anditign; 22 °C, 0% relative humidity.

flaterial and gguipment:

- Standard reference material 1470 for gas transmission with
known permeability of 69.104 cc./m2.day.atm.

- Mocon Oxtran 100 Oxygen Permeability tester, load resistor
53 ohm.

Ergceduze:

- Conduct the permeability test of the standard reference
sample.

- Calculate oxygen transmission of 1 mV output.

Result and discussign:

The permeability of this standard was equal to 4.45 mV.

Therefore, the conversion factor C

C

69.104 cc/m2.day /4.45 mV

C 15.53 cc/m2.day.

The transmission output from the Oxtran in mV unit can be

converted to permeance value in unit cc oxygen/m2.day.atm. , as

follow;

Permeance = Response output (mV)* Conversion factor* Area
conversion factor/ Partial pressure of oxygen.

Area conversion factor; non-masked sample = 1

masked sample = 10

Partial pressure of oxygen = .21 atm

74

Appendix 7

Oxygen Permeance Data under 0 ppm and 1 ppm Ethanol at 0% an

Table 10: Oxygen Permeance of Polystyrene 1.1 mil

at 23 °C (0% ethanol).

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)
0.0 0.00 0.00

1.2 0.10 75.54

1.8 1.00 745.44

2.4 2.80 2087.23

3.0 3.80 2832.67
3.6 4.65 3466.29

4.2 4.95 3689.93

4.8 5.15 3839.02
6.0 5.25 3913.56
7.2 5.30 3950.87
13.2 5.40 4025.38
56.4 5.45 4062.65
79.2 5.50 4099.95

75

'Table 11: Oxygen Permeance of Polystyrene 1.1 mil
at 24 °C (1 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)
0.0 0.00 10.00
6.6 0.00 0.00
11.4 0.00 0.00
13.8 0.10 74.54
16.2 0.45 335.45
18.6 1.00 745.44
21.0 1.50 1118.16
24.6 2.30 1714.51
29.4 3.10 2310.86
33.0 3.55 2646.31
40.2 4.20 3130.85
43.8 4.40 3279.94
51.0 4.70 3503.57
55.8 4.80 3578.11
61.8 4.90 3652.66
66.6 5.00 3727.20
71.4 5.05 3764.47
83.4 5.10 3801.74
96.6 5.15 3839.02

"'3.

I1:

76

Table 12: Oxygen Permeance of Saranex 2 mil
at 24 °C (0 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc./m2.day.atm.)
0.0 0.000 0.00
1.2 0.000 0.00
2.4 0.000 0.00
3.0 0.000 0.00
4.2 0.005 0.37
5.4 0.020 1.49
6.6 0.045 3.35
7.8 0.070 5.22
8.4 0.080 5.96
9.0 0.090 6.71
10.8 0.110 8.19
12.0 0.120 8.95
14.4 0.130 9.69
21.6 0.140 10.44
32.4 0.140 10.44

77

Table 13: Oxygen Permeance of Saranex 2 mil.
at 24 °C (1 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc./m2.day.atm.)
3.6 0.00 0.00
7.2 0.00 0.00
9.6 0.00 0.00
12.0 0.00 0.00
14.4 0.00 0.00
20.4 0.02 1.12
24.0 0.04 2.61
27.6 0.06 4.09
30.0 0.07 4.85
32.4 0.08 5.59
34.8 0.07 6.34
38.4 0.10 7.08
43.2 0.11 7.83
49.2 0.12 8.57
60.0 0.13 9.32
84.0 0.14 10.06
105.6 0.14 10.44

109.2 0.14 10.44

78

Table 14: Oxygen Permeance of PET 0.7 mil
at 24 °C (0 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)
0.0 0.000 0.00
2.4 0.000 0.00
3.6 0.000 0.00
4.8 0.005 0.37
7.2 0.025 1.86
10.8 0.070 5.22
15.6 0.120 8.95
18.0 0.140 10.45
20.4 0.160 11.93
25.2 0.190 14.16
28.8 0.210 15.65
33.6 0.230 17.15
37.2 0.240 17.86
42.0 0.250 18.64
46.8 0.260 19.38
52.8 0.270 20.13
62.4 0.280 20.87
79.2 0.290 21.62
93.6 0.295 21.99
99.6 0.295 21.99

79

Table 15: Oxygen Permeance of PET 0.7 mil
at 24 °C (1 ppm Ethanol)

Time . Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)
0.0 0.000 0.00
2.4 0.000 0.00
4.8 0.000 0.00
8.4 0.000 0.00
10.8 0.000 0.00
16.8 0.000 0.00
21.6 0.005 0.37
25.2 0.020 1.49
27.6 0.030 2.24
30.0 0.040 2.98
36.6 0.060 4.47
40.2 0.080 5.96
46.2 0.110 8.19
48.6 0.120 8.95
53.4 0.040 10.44
61.8 0.070 12.67
67.8 0.190 14.16
72.6 0.200 14.91
77.4 0.210 15.65
83.4 0.220 16.39
89.4 0.230 17.15
99.0 0.230 17.89
113.4 0.250 18.64
127.8 0.255 19.01
142.2 0.260 19.38
148.2 0.260 19.38

 

80

Table 16: Oxygen Permeance of LDPE 1.5 mil
at 23 °C (0 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)
0.0 0.00 0.00
0.6 0.00 0.00
1.2 0.20 149.09
1.8 1.35 1006.34
2.4 2.90 2161.78
3.0 4.00 2981.76
3.6 4.80 3578.11
4.2 5.20 3876.29
4.8 5.50 4099.92
5.4 5.70 4249.01
6.0 5.75 4286.28
7.2 5.85 4360.82
8.4 5.90 4398.09
15.6 5.95 4435.37
26.4 6.00 4472.64
32.4 6.00 4472.64

 

81

Table 17: Oxygen Permeance of LDPE 1.5 mil
at 24 'P (1 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc [m2 . day. atm)

0.0 0.00 0.00
2.4 0.00 0.00
4.8 0.00 0.00
7.2 0.00 0.00
9.6 0.05 37.27
10.8 0.20 149.09
13.2 0.90 670.89
14.4 1.30 969.07
15 1.75 1304.52
16 2.20 1639.97
18 2.60 1938.14
19 3.00 2236.32
20 3.30 2459.95
21 3.65 2720.86
22 8 3.95 2944.49
25 2 4.44 3309.75
27 4.85 3615.38
30 5.15 3839.02
33 5.50 4099.92
38 5.80 4323.55
43 6.00 4472.64
48 6.10 4547.18
58 6.20 4621.73
81 6.30 4692.27

 

82

Table 18: Oxygen Permeance of Cellulose Acetate
1 mil at 24 °C (0 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)
0.0 0.00 0.00
0.6 0.00 0.00
1.8 0.60 447.26
2.4 1.45 1080.89
3.0 2.35 1751.78 r“
3.6 2.75 2049.96
4.2 3.05 2273.59
4.8 3.20 2497.22
9.0 3.40 2534.49 5'
32.4 3.45 2571.77

 

83

Table 19: Oxygen Permeance of Cellulose Acetate
1 mil at 24 'C (1 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm.)
0.0 0.00 0.00
2. 0.00 0.00
4. 0.00 0.00
6. 0.00 0.00
8. 0.25 186.36
10 0.88 652.26
13 1.48 1103.25
14 1.73 1289.61
15.6 1.95 1453.61
16 8 2.15 1602.69
18 2.30 1714.51
19 2.45 1826.31
21 2.68 1997.78
24 0 2.85 2124.50
26 4 2.98 2217.68
30 3.10 2310.86
34 3.20 2385.41
37 3.25 2422.68
44 3.30 2459.95
49 2 3.33 2482.32
66 3.35 2497.22
118 3.38 2519.59

 

84

Table 20: Oxygen Permeance of Polyvinyl Acetate
0.8 mil at 26 ‘C (0 ppm Ethanol).

 

Time Recording Output Oxygen Permeance

(min) (mV) (cc/m2.day.atm)
0.0 ‘ 0.00 0.00
0.6 0.00 0.00
1.8 0.25 186.36
2.4 0.58 428.63
3.0 0.83 614.99
3.6 0.95 708.17
4.2 1.03 764.08
4.8 1.08 801.35
6.0 1.10 819.99
10.8 1.13 838.62
22.8 1.15 857.26

85

Table 21: Oxygen Permeance of Polyvinyl Acetate
0.8 mil at 24 °C (1 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)
0.0 0.00 0.00
1.2 0.00 0.00
2.4 0.00 0.00
3.6 0.00 0.00
4.8 0.00 0.00
6.6 0.05 37.27
7.8 0.15 111.82
9.0 0.29 216.18
10.2 0.41 305.63
11.4 0.52 387.63
12.6 0.61 454.72
13.8 0.69 514.35
15.0 0.75 559.08
16.2 0.80 596.35
17.4 0.85 633.62
18.6 0.88 655.99
19.8 0.91 678.35
21.0 0.94 700.71
22.2 0.96 715.62
23.4 0.98 730.53
25.8 1.01 752.89
27.0 1.02 760.35
34.2 1.04 775.26
40.2 1.05 782.71
48.6 1.06 790.17
67.8 1.07 797.62
87.0 1.07 797.62

 

86

Table 22: Oxygen Permeance of Polyvinyl Butyral
1 mil at 23 °C (0 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)

0.0 0.00 0.00

1.2 0.05 37.27

2.4 1.50 1118.16

3.6 2.90 2161.78

4.8 3.45 2571.77

6.0 3.60 2683.58

7.2 3.70 2758.13

8.4 3.75 2795.40

9.6 3.77 2810.31

12.0 3.80 2832.67

21.6 3.90 2907.22

30.0 3.95 2944.49

38.4 4.00 2981.76

54.0 4.05 3019.03

69.6 4.10 3056.30

70.8 4.10 3056.30

 

 

87

Table 23: Oxygen Permeance of Polyvinyl Butyral
1 mil at 22 °C (1 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min (mV) (cc/m2.day.atm)
0.0 0.00 0.00
4.8 0.00 0.00
9.6 0.00 0.00
10.8 0.05 37.27
12.0 0.15 111.82
14.4 0.60 447.26
16.8 1.10 819.98
19.2 1.50 1118.16
22.8 2.00 1490.88
26.4 2.40 1789.06
30.0 2.70 2012.69
33.6 -2.90 2161.78
38.4 3.10 2310.86
42.0 3.20 2385.41
46.8 3.30 2459.95
54.0 3.40 2534.49
73.2 3.50 2609.04

124.8

3.55

2646.31

 

88

Table 24: Oxygen Permeance of Ethylene Vinyl Acetate
0.8 mil at 24 °C (0 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)
0.0 0.00 0.00
0.6 0.00 0.00
1.2 0.30 223.63
1.8 2.40 1789.06
2.4 5.40 4025.38
3.0 8.40 6261.69
3.6 10.30 7678.03
4.2 11.60 8647.10
4.8 12.50 9318.00
5.4 13.00 9690.72
6.0 13.40 9988.89
6.6 13.70 10212.53
7.2 13.80 10287.07
10.8 14.20 10585.25
19.2 14.40 10734.34
32.4 14.50 10808.88

55.2 14.60 10883.42

89

Table 25: Oxygen Permeance of Ethylene Vinyl Acetate
0.8 mil at 24 °C (1 ppm Ethanol).

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)
0.0 0.00 0.00
2.4 0.00 0.00
4.8 0.00 0.00
6.0 0.00 0.00
8.4 0.40 298.18
9.6 1.00 745.44
10.8 2.10 1565.42
12.0 3.50 2609.04
13.2 4.70 3503.57
14.4 5.80 4323.55
15.6 7.10 5292.62
16.8 8.00 5963.52
18.0 8.90 6634.42
20.4 10.30 7698.03
22.8 11.40 8498.02
26.4 12.60 9392.54
28.8 13.20 9839.81
33.6 14.00 10436.16
38.4 14.50 10622.52
43.2 14.80 11032.51
54.0 15.10 11256.14
66.0 15.20 11130.69
98.4 15.10 11256.14
109.2 15.10 11256.14

 

90

Table 26: Oxygen Permeance of Polyvinyl Chloride 1.0
mil at 24 °C (0 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)
0.0 0.00 0.00
0.6 0.00 0.00
1.2 0.00 0.00
1.8 1.60 1192.70
2.4 3.20 2385.41
3.0 5.40 4025.38
3.6 7.10 5292.62
4.2 8.20 6112.61
4.8 8.80 6559.87
5.4 9.20 6858.05
6.0 9.20 7081.68
6.6 9.50 7156.22
7.2 9.60 7230.77
9.6 9.80 7305.31
13.2 9.90 7379.86
37.2 10.00 7454.40
48.0 10.00 7454.40

 

91

Table 27: Oxygen Permeance of Polyvinyl Chloride 1.0
mil at 24 °C (1 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)
0.0 0.00 0.00
2.4 0.00 0.00
4.8 0.00 0.00
7.2 0.30 223.63
8.4 1.00 745.44
9.6 1.90 1416.34
10.8 2.80 2087.23
12.0 3.80 2832.67
13.2 4.60 3429.02
14.4 5.40 4025.38
16.8 6.70 4994.45
19.2 7.60 5665.34
21.6 8.20 6112.61
25.2 8.80 6559.87
28.8 9.20 6858.05
32.4 9.40 7007.14
38.4 9.60 7156.22
50.4 6.70 7230.77
66.0 9.80 7305.31

92

Table 28: Oxygen Permeance of Polypropylene 0% Ceramic
0.9 mil at 23 °C (0 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2 . day. atm)
0.0 0.00 0.00
0.6 0.00 0.00
1.2 0.05 37.27
1.8 0.80 596.35
2.4 2.05 1490.88
3.0 3.30 2459.95
3.6 4.20 3130.85
4.2 4.80 3578.11
4.8 5.20 3876.29
5.4 5.45 4062.65
6.0 5.60 4174.46
6.6 5.70 4249.01
7.2 5.80 4323.55
9.6 5.90 4398.09.
15.6 5.95 4435.37
26.4 6.00 4472.64
31.2 6.00 4472.64

93

Table 29: Oxygen Permeance of Polypropylene 0% Ceramic
0.9 mil at 23 °C (1 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)
0.0 0.00 0.00
2.4 0.00 0.00
4.8 0.00 0.00
7.2 0.00 0.00
9.6 0.15 111.82
12.0 0.95 708.17
13.2 1.45 . 1080.89
14.4 1.90 1416.34
16.8 2.70 2012.67
20.4 3.60 2683.58
25.2 4.40 3279.94
28.8 4.80 3578.11
31.2 5.00 3727.20
34.8 5.20 3876.29
37.2 5.30 3950.83
62.6 5.70 4249.01
79.4 5.75 4286.28

 

94

Table 30: Oxygen Permeance of Polypropylene 3% Ceramic
1.4 mil at 23 °C (0 ppm) Ethanol

 

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)
0.0 0.00 0.00
1.2 0.00 0.00
1.8 0.40 298.18
2.4 1.50 1118.16
3.0 2.80 2087.23
3.6 3.80 2832.67
4.2 4.60 3429.02
4.8 5.05 3764.47
5.4 5.40 4025.38
6.0 5.55 4137.19
6.6 5.70 4249.00
8.4 5.80 4323.55
10.2 5.90 4398.09
15.0 5.95 4435.37
27.0 6.00 4472.64
33.0 6.00 4472.64

 

 

95

Table 31: Oxygen Permeance of Polypropylene 3% Ceramic
1.4 mil at 23 °C (1 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)
0.0 0.00 0.00
2.4 0.00 0.00
4.8 0.00 0.00
7.2 0.00 0.00
10.8 0.20 149.29
12.0 0.50 372.72
13.2 0.90 670.89
14.4 1.30 969.07
15.6 1.70 1267.25
16.8 2.15 1602.69
19.2 2.90 2161.78
22.8 3.80 2832.67
26.4 4.45 3317.21
34.8 5.30 3950.83
38.4 5.50 4099.92
45.6 5.75 4286.28
54.0 5.90 4398.09
73.2 6.00 4472.64
100.8 6.10 4547.18
118.8 6.15 4584.46

96

Table 32: Oxygen Permeance of Polypropylene 7% Ceramic
1.8 mil at 21 °C (0 ppm Ethanol)

Time ' Recording Output Oxygen Permeance
(min) (mV) (cc/m2. day.atm)
0.0 0.00 0.00
0.6 0.00 0.00
1.2 0.00 0.00
1.8 0.25 186.36
2.4 0.80 596.35
3.0 1.50 1118.16
3.6 2.00 1490.88
4.2 2.35 1751.78
4.8 2.55 1900.87
5.4 2.70 2012.69
6.0 2.75 2049.96
6.6 2.80 2087.23
16.8 2.90 2161.78
21.6 2.90 2161.78

97

Table 33: Oxygen Permeance of Polypropylene 7% Ceramic
1.8 mil at 23 °C (1 ppm Ethanol)

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)
-0.0 0.00 0.00
2.4 0.00 0.00
4.8 0.00 0.00
7.2 0.00 0.00
8.4 0.10 74.54
9.6 0.40 298.18
10.8 0.70 521.81
12.0 1.00 745.44
13.2 1.25 931.80
14.4 1.50 1118.16
15.6 1.70 1267.25
16.8 1.90 1416.34
20.4 2.30 1714.52
24.0 2.50 1863.60
28.8 2.70 2012.69
32.4 2.80 2087.23
40.8 2.90 2161.78
51.6 2.95 2199.05
68.4 3.00 2236.32

98

Table 34: Oxygen Permeance of Polypropylene 3% Ceramic
1.4 mil at 23 °C (0 ppm Ethanol, Tenax Pathway).

Time Recording Output Oxygen Permeance
(min) (mV) (cc/m2.day.atm)
0.0 0.00 0.00
2.4 0.00 0.00
4.8 0.05 37.27
6.0 0.20 149.09
7.2 0.60 447.26
8.4 1.00 745.48
9.6 1.45 1080.89
10.8 1.90 1416.34
13.2 2.60 1938.14
15.6 3.25 2422.68
18.0 3.75 2795.40
20.4 4.15 3093.58
22.8 4.50 3354.48
34.2 5.05 3764.47
37.8 5.30 3950.83
42.6 5.50 4099.92
46.2 5.60 4174.46
49.8 5.70 4249.01
57.0 5.80 4323.55
70.2 5.90 4398.09
75.0 5.90 4398.09

 

99

Appendix 8

Determination of the Repeatability of the Experiments

The repeatability of the experiments was estimated by

determining the oxygen permeance of a masked sample of LDPE

1.5 mil three times (at 23 °C, 0% RH). The oxygen permeance

data is as shown below.
Trail
1
2
3
Average

Oxygen Permeance
(cc/m2 . day . atm)
4524

4289

4252

4355

The estimated percent standard error is 3%.

. .7

 

 

100

Appendix 9

Table 35: Activation Energy of Polymer Samples
(Polymer Handbook, 1975)

Film Activation Energy
(cal/mole)
""" 13E?“'m"'"ZESSTES"""""'

SARAN 15,833.30

LDPE 10,738.10

PVC 13,238.10

EVAc 13,357.10
Cellulose

Acetate 4,976.20

PVAc 13,557.10

PVB* 11,904.76

PP 11,357.10

* Estimated value

 

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