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UBC Theses and Dissertations
Rheology and processability of teflon FEP resins for wire coating Rozenbaoum, Evgueni E.
Abstract
Experiments were carried out in both parallel plate and capillary rheometers for a variety of tetrafluoroethylene/hexafluoropropylene (TFE/HFP) copolymers and TFE/HFP/per-fluoro(alkyl vinyl ether) (TFE/HFP/PAVE) terpolymers, also known as Teflon® FEP polymers, having different molecular weights and compositions (HFP and PAVE content). The critical conditions for the onset of melt fracture and the influence of temperature, molecular weight, and composition of the resins are determined. The critical molecular weight for the onset of entanglements was found to be about 100,000, a value much higher than those previously reported. The relationships between the processability of the wire coating Teflon® FEP resins and their composition, viscosity, ability to crystallize, and melt elasticity were established. The experimental data were used for a thorough rheological modeling of the behavior of these resins. The latter includes calculation of their linear relaxation time spectra and nonlinear parameters using a multimode Phan-Thien and Tanner (PTT) constitutive equation. A new data analysis procedure based on a mathematical model for the nonisothermal capillary flow of polymer melts coupled with heat transfer is developed. The computer simulations proposed can be used to provide detailed velocity, temperature, and pressure distributions and to recover the parameters of the employed slip velocity model corrected for the effect of viscous heating. Finally, the effect of various processing aids on the processability of fluoropolymers and polyolefins during extrusion and wire coating was studied. It was found that polyethylene works as a processing aid in the extrusion of Teflon® FEP resins in the same way as fluoropolymers do in the extrusion of polyolefins. Finally, the processing additive based on a boron nitride (BN) composition was found to eliminate sharkskin melt fracture and postpone gross melt fracture to significantly higher shear rates for a variety of polymers.
Item Metadata
| Title |
Rheology and processability of teflon FEP resins for wire coating
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| Creator | |
| Publisher |
University of British Columbia
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| Date Issued |
1998
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| Description |
Experiments were carried out in both parallel plate and capillary rheometers for a
variety of tetrafluoroethylene/hexafluoropropylene (TFE/HFP) copolymers and
TFE/HFP/per-fluoro(alkyl vinyl ether) (TFE/HFP/PAVE) terpolymers, also known as
Teflon® FEP polymers, having different molecular weights and compositions (HFP and
PAVE content). The critical conditions for the onset of melt fracture and the influence of
temperature, molecular weight, and composition of the resins are determined. The critical
molecular weight for the onset of entanglements was found to be about 100,000, a value
much higher than those previously reported. The relationships between the processability
of the wire coating Teflon® FEP resins and their composition, viscosity, ability to
crystallize, and melt elasticity were established. The experimental data were used for a
thorough rheological modeling of the behavior of these resins. The latter includes
calculation of their linear relaxation time spectra and nonlinear parameters using a multimode
Phan-Thien and Tanner (PTT) constitutive equation.
A new data analysis procedure based on a mathematical model for the
nonisothermal capillary flow of polymer melts coupled with heat transfer is developed.
The computer simulations proposed can be used to provide detailed velocity,
temperature, and pressure distributions and to recover the parameters of the employed
slip velocity model corrected for the effect of viscous heating. Finally, the effect of
various processing aids on the processability of fluoropolymers and polyolefins during
extrusion and wire coating was studied. It was found that polyethylene works as a
processing aid in the extrusion of Teflon® FEP resins in the same way as fluoropolymers
do in the extrusion of polyolefins. Finally, the processing additive based on a boron
nitride (BN) composition was found to eliminate sharkskin melt fracture and postpone
gross melt fracture to significantly higher shear rates for a variety of polymers.
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| Extent |
11355153 bytes
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| Genre | |
| Type | |
| File Format |
application/pdf
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| Language |
eng
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| Date Available |
2009-06-25
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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 |
10.14288/1.0058639
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| URI | |
| Degree | |
| Program | |
| Affiliation | |
| Degree Grantor |
University of British Columbia
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| Graduation Date |
1998-11
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| Campus | |
| Scholarly Level |
Graduate
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| Aggregated Source Repository |
DSpace
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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.