AN INVESTIGATION OF THE BLEND OF PARTIALLY BROMINATED POLY(2,6-DIMETHYL 1,4-PHENYLENE OXIDE) AND POLYSTYRENE IN THE PRIMARY (GLASS-TO-RUBBER) TRANSITION REGION

Compatible polymer blends can be used to test critically the viability of the damped Debye lattice (DDL) model of relaxation in the primary (glass-to-rubber) transition region. The model predicts an unusual sharpening of the stress relaxation master curve of a marginally two-dimensional DDL upon dilution with a plasticizer. We have prepared an appropriate two-dimensional DDL by adding modest amounts of partially brominated poly(2,6-dimethyl 1,4-phenylene oxide) to polystyrene to form compatible blends. As predicted by the model, sharpening of the stress relaxation behavior upon dilution was observed for all blend compositions and for all diluents used. However, at higher brominated poly(phenylene oxide) concentrations, the anticipated diluent concentration dependence was not always obesrved and the sharpening of the stress relaxation behavior was less than expected.