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The effects of long chain branching on the rheological properties of polymers Giumanca, Radu
Abstract
Long chain branching (LCB) is a very important feature in polymer science due to its influence on the rheological properties of polymers. It has been shown that long chain branching causes strain hardening behavior in the extensional flow of polymer, feature which is not seen in linear species. A great industrial interest has been shown in a method which would detect long chain branching by a simple, yet robust method. Fifteen different samples of polypropylene (PP) of varying molecular weights (MW) and branching structures were studied. The aim was to obtain linear viscoelastic measurements using a Rheometrics System IV rheometer and compare the results to determine the effects of backbone MW, branch MW, and number of branches on the polymers' viscoelastic properties. It was discovered that the samples exhibit drastic thermal degradation, even under inert atmosphere. An antioxidant (Irganox 1010) was found to have no effect. A comparison of linear viscoelastic data yielded questionable results, perhaps suggesting a higher than expected polydispersity. Samples of comb-structure polystyrene were also studied. Linear viscoelastic data was obtained for two different series of PS, differing in MW and branch MW. By comparing with previously obtained data, it was discovered that time (~20 years) has had a small effect for most of the samples. Non-linear measurements were also obtained, and the results for the most part agree with published data. The differences, especially an extended plateau feature previously unpublished, are discussed.
Item Metadata
Title |
The effects of long chain branching on the rheological properties of polymers
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2002
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Description |
Long chain branching (LCB) is a very important feature in polymer science due to
its influence on the rheological properties of polymers. It has been shown that long chain
branching causes strain hardening behavior in the extensional flow of polymer, feature
which is not seen in linear species. A great industrial interest has been shown in a method
which would detect long chain branching by a simple, yet robust method.
Fifteen different samples of polypropylene (PP) of varying molecular weights
(MW) and branching structures were studied. The aim was to obtain linear viscoelastic
measurements using a Rheometrics System IV rheometer and compare the results to
determine the effects of backbone MW, branch MW, and number of branches on the
polymers' viscoelastic properties. It was discovered that the samples exhibit drastic
thermal degradation, even under inert atmosphere. An antioxidant (Irganox 1010) was
found to have no effect. A comparison of linear viscoelastic data yielded questionable
results, perhaps suggesting a higher than expected polydispersity.
Samples of comb-structure polystyrene were also studied. Linear viscoelastic data
was obtained for two different series of PS, differing in MW and branch MW. By
comparing with previously obtained data, it was discovered that time (~20 years) has had
a small effect for most of the samples. Non-linear measurements were also obtained, and
the results for the most part agree with published data. The differences, especially an
extended plateau feature previously unpublished, are discussed.
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Extent |
2910462 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-09-18
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0058665
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2002-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.