ORIENTATION AND RELAXATION IN UNIAXIALLY STRETCHED POLY(METHYL METHACRYLATE)-POLY(STYRENE-CO-ACRYLONITRILE) COMPATIBLE BLENDS

The orientation and relaxation of both polymer chains in compatible bl ends of poly(methyl methacrylate)-poly(styrene-co-acrylonitrile) (PMMA -SAN) have been studied using Fourier transform infra-red spectroscopy . The influence of strain rate and stretching temperature on orientati on have been measured. In these blends, where inter-chain interactions are almost nonexistent, both polymers orient differently over the who le concentration range, with the PMMA chains being always more oriente d than the SAN chains. Orientation relaxation master curves have also been established. A change in molecular weight between entanglements d oes not seem to be the main factor influencing orientation and relaxat ion, but use of the monomeric friction coefficient, which reflects loc al mobility and interactions, as a scaling factor allows one to obtain two general master curves which are representative of the overall beh aviour of the PMMA and SAN chains in their compatible blends.