The influence of blending polystyrenes of narrow molecular weight distribution on melt creep flow and creep recovery in elongation

Creep and creep recovery experiments in elongation were performed with melts of anionically polymerized polystyrenes (PS) and with their blends at a temperature of 150 °C. For stresses₀ < 10 000 N/m² the samples with narrow molecular weight distribution show linear viscoelastic behavior up to the maximum Hencky strain = 3.5, achievable in a newly developed elongational rheometer for polymer melts. The compliances,D (t), of the blends are linear-viscoelastic only up to a strain limit_L. For strains beyond_L the compliance of each blend depends on the stress₀. For a series of binary blends, prepared from the same components of narrow MWD, the linear-viscoelastic limit_L seems to be independent of the mixing ratio and stress._L seems to be a function only of the molecular weights of the original components, the blends investigated were made from.Paper presented at the Annual Conference of the German Society of Rheology at Ulm, March 7–10, 1983.