ISSN:
0323-7648
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Biaxial extensional flow behavior of monodisperse polystyrene melts has been investigated by using a lubricated squeezing flow method at constant strain rates. Master curves for the biaxial stress growth coefficient ηB+ are obtained by applying the time-temperature superposition principle. The coefficient ηB+ deviates from a linear viscoelastic curve at very small strain such as 0.1, and then approaches a quasi steady state. The quasi-steady-state viscosity ηB,qs decreases with the strain rate ηB. At very small strain rates, the coefficient ηB+ increases again after the quasi steady state and becomes much larger than the linear viscoelastic curve. The strain rate dependence curves of ηB,qs obtained for different molecular weight samples can be superposed to give a super master curve using the weight-average relaxation time η0 as a reducing parameter. It is found that the biaxial viscosity ηB,qs begins to decrease at much smaller reduced strain rate (∊Bτ0=0.01) compared with the shear viscosity, which begins to decrease at reduced strain rate of about 1.0.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/actp.1995.010460309
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