TENSILE YIELD PARAMETERS FOR POLY(VINYL CHLORIDE) BLENDS WITH A METHYL-METHACRYLATE ETHYL ACRYLATE COPOLYMER

Tensile yield measurements were made on blends of poly(vinyl chloride) (PVC) with a methyl methacrylate/ethyl acrylate 90/10 copolymer (CP-A) covering a blend range of 0 to 50 wt% CP-A, a temperature range of -50 to 50-degrees-C and a strain-rate range of 10(-3) to 10(0) s-1. Increasing CP-A level in PVC has the same effect on the brittle-to-ductile transition as does decreasing temperature or increasing strain rate in neat PVC. The maximum stresses observed for these blends tend to be independent of CP-A level over the low-concentration range, i.e. < 25 wt%, but they do decrease over the 50 wt% range. The tensile yield stress variation with temperature and strain rate was represented in terms of the Ree-Eyring-Roetling rate model. This model represents the experimental data within experimental error. The tensile yield beta process parameters were compared to those determined from viscoelastic measurements on these same blends. The activation energies were found to be the same for the viscoelastic and tensile yield measurements, while the entropies of activation were found to be proportional.