VISCOELASTIC PROPERTIES OF STYRENE-CO-METHYL METHACRYLATE RANDOM COPOLYMERS

Viscoelastic properties of styrene-co-methyl methacrylate random copolymers have been determined over a temperature range covering the glass transition, the rubbery plateau, and the terminal zone and compared with polystyrene and polymethyl methacrylate homopolymers. Nonlinear behavior was observed in the variations of most of the physical and rheological characteristics with the methyl methacrylate content in the copolymer. Results are interpreted in terms of the rupture of polar-polar intermolecular interactions between ester groups due to the presence of styrene units.