New extensional rheometer for elongational viscosity and flow birefringence measurements: some results on polystyrene melts |
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| Authors: | R. Muller D. Froelich |
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| Affiliation: | Université Louis Pasteur, Ecole d''Application des Hauts Polymères, 4, rue Boussingault, 67000 Strasbourg, France |
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| Abstract: | A new extensional rheometer allowing the simultaneous measurement of elongational viscosity and flow birefringence is described. Polystyrene melts have been tested at different temperatures and strain rates. It appears that the time-temperature superposition principle holds for elongational tests in the temperature range investigated, with the same shift factors as for linear shear experiments. It has been verified that the stress optical behaviour of the melts is linear for small values of the stress whereas significant deviations appear at higher stresses. |
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| Keywords: | polymer melt rheology elongational viscosity polystyrene flow birefringence extensional rheometer time-temperature equivalence |
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