Viscoelastic behavior of low molecular weight polystyrene

Abstract

Abstract The shear creep and creep recovery behavior of narrow molecular weight distribution polystyrene samples of low molecular weight, 1.1 × 10 3 , 3.4 × 10 3 , and 1.57 × 10 4 are reported as a function of temperature, near and above the glass temperature. Time‐temperature equivalence for the total creep compliance is found to be nonapplicable, and in fact the steady‐state recoverable compliance, J e , is a strong function of temperature. The time‐scale shift factors for the recoverable compliance are analyzed in the light of free volume theory. Viscosity data are presented for samples with molecular weights between 1.1 × 10 3 and 6.0 × 10 5 . The temperature dependence of the characteristic time constant η J e can be explained in terms of free volume concepts whereas that of viscosity η cannot. Effects of residual molecular weight heterogeneity are demonstrated.