Mechanical properties of polystyrene and polypropylene based materials after exposure to hydrogen peroxide

126 Pages·1999·6.236 MB·English

by  John M. Torres

Rochester Institute of Technology
RIT Scholar Works
Theses Thesis/Dissertation Collections
1999
Mechanical properties of polystyrene and
polypropylene based materials after exposure to
hydrogen peroxide
John Torres
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Mechanical Properties ofPolystyrene and Polypropylene Based Materials
After Exposure to Hydrogen Peroxide
By
John M. Torres
Athesis submitted inpartial fulfillment ofthe
requirements forthe degree ofMaster ofScience inthe
DepartmentofPackaging Science
inthe College ofApplied Science and Technology
ofthe RochesterInstitute ofTechnology.
December, 1999
College ofApplied Science and Technology
Rochester Institute ofTechnology
Rochester, New York
CERTIFICATE OF APPROVAL
M.S. DEGREE THESIS
The M.S. degree thesis ofJohn M. Torres
has been examined and approved
by the thesis committee as satisfactory
for the thesis requirements for the
Master ofScience Degree.
FritzJ.Yambrach
Dr.DavidL.Olsson
StephenYucknut
Date
Thesis ReproductionPermissionStatement
ROCHESTER INSTITUTE OF TECHNOLOGY
COLLEGE OF APPLIED SCIENCE AND TECHNOLOGY
Title ofThesis: MechanicalProperties ofPolystyrene and Polypropylene Based
Materials after Exposureto HydrogenPeroxide.
I, John M. Torres, prefer to be contacted eachtime a request for reproduction is made. If
permission is granted, any reproduction will not be for commercial use or profit. I can be
reached at the following address:
PO Box 8524
Tarrytown, NY 10591
[phone]
/I_t;-J/"-q--'~
Date: _,,---.+..-· _
I I
Abstract
This study addresses a specific problem faced by a company in the food industry,
although all food companies face similar issues. In an effort to reduce costs, the pursuit
to down-gauge packaging materials is constant. In the case of this study, the primary
package of a dairy product is being considered for reduction from the current 57 mil
thickness to 52 mils. Inthe past, as the material was down-gauged from 62 mils, a loss in
material strength and an increase in damage were observed. Initial research into the issue
by line personnel found that the increase in damage was occurring when the forming
equipment stopped running and material was held in the hydrogen peroxide (H202) and
heating tunnels for extended amounts of time. Further investigation confirmed that
extended durations of the material submerged in the H202 sterilization tank caused the
material to embrittle.
Therefore, this study was constructed to determine the effects of H202 on two
materials, polystyrene and polypropylene, and at two thickness', 57 and 52 mils, and 55
and 50 mils, respectively. The materials were exposed to increasing durations ofH202, 0
time, 20 seconds, 60 seconds, 120 seconds, 300 seconds, 600 seconds, 1200 seconds, and
subsequently tested for tensile strength, elongation, and modulus of elasticity. It was
expected that these properties would decrease as the exposure was increased, but the
results didnot demonstratethat.
The polystyrene based material exhibited very little, or no, change in mechanical
properties that could be attributed to H202. Indications were that any variations in
mechanical properties were based more on other factors, such as materials impurities or
variations in the extrusion process, than the exposure to H202. The polypropylene based
material did exhibit some relation between material properties and exposure to H202.
Although these changes were very small and left significant doubt as to their negative
impact inthe aseptic process.
Ill
Acknowledgements
I would like to thank Fritz Yambrach for being my thesis advisor and providing
me with the guidance necessary to conduct effective research. He has been supportive
throughout my research and kept me moving forward. I would also to thank Dr. Olsson
for providing important direction on general thesis guidelines. And I would like to thank
Steve Yucknut forbeing apositive influence and consistently pushing me to complete my
research while allowing me the time to do it. I would also like to thank Al delCastillo,
who has always been supportive and helped me in anyway necessary. Finally, I would
like to thank my Father and Mother, who have made my education possible and through
their support and guidance have givenme the opportunityto make this thesis possible.
IV
Table ofContents
Abstract
i
Acknowledgements iii
Table ofContents iv
List ofTables vi
List ofFigures vii
I. Introduction 1
A. Sterile Packaging ofFood 1
1 Product Preservation 2
.
a. Chemical 2
b. Biological 3
c. Physical 3
2. Package Sterilization 6
a. Canning 7
b. Aseptic 10
c. Radiation 12
B. ShelfLife 13
1 Product 14
.
a. Perishability 14
b. BulkDensity 14
2. Environment 15
a. Climatic 15
b. Physical 16
3. Package 16
a. MVTR 17
b. OTR 18
II. Focus ofResearch 19
III. Hypothesis 24
A. Materials 24
B. Material Degredation 26
C. Statement ofProblem 27
D. Research Proposal 29
IV. Methodology 30
A. Test Description 30
1. Tensile Strength: ASTM - D638 30
2. Elongation: ASTM - D638 31
3. Modulus ofElasticity: ASTM - D638 31
B. Testing Preparation 31
1. Material Variables 32
a. Polystyrene Material 32
b. Polypropylene Material 33
2. Sample Size and Preparation 34
C. Testing Procedure 35
V. Results 39
A. DataAnalysis 39
1. F-ratio 39
2. Coefficient ofCorrelation 42
3. Coefficient ofDetermination 44
a. Tensile Strength 45
b. Elongation @ Break 46
c. Elongation @ Yield 46
d. Modulus ofElasticity 47
VI. Conclusion & Recommendation 48
A. Discussion ofResults 48
1. Polystyrene 57 mil 48
2. Polystyrene 52 mil 50
3. Polypropylene 55 mil 51
4. Polypropylene 50 mil 53
5. Scanning ElectronMicroscope Photographs 54
B. Recommendations for Further Study 56
Work Cited 57
Appendix A ScatterPlots 59
Appendix B RawData 65
Appendix C Regression Results 81
Appendix D SEM Photographs 97
Appendix E ANOVA Results 99
Appendix F Critical Values ofF Table 115
VI
List ofTables
Table 4.1 Materials Selected for Testing 33
Table 5.1 Tensile Strength- F values 41
Table 5.2 Elongation @ Break- F values 41
Table 5.3 Elongation @ Yield- F values 42
Table 5.4 Modulus ofElasticity- F values 42
Table 5.5 Tensile Strength- Correlation 45
Table 5.6 Elongation @ Break- Correlation 46
Table 5.7 Elongation @ Yield- Correlation 46
Table 5.8 Modulus ofElasticity- Correlation 47
Table 6.1 Polystyrene 57 mil- DataAnalysis 49
Table 6.2 Polystyrene 52 mil- DataAnalysis 50
Table 6.3 Polypropylene 55 mil- DataAnalysis 53
Table 6.4 Polypropylene 50 mil- DataAnalysis 54