STRUCTURE AND RHEOLOGY OF STYRENE METHYL-METHACRYLATE COPOLYMERS

In a series of homopolymers and copolymers of styrene (S) and methyl methacrylate (MMA) (100/0, 85/15, 50/50, 15/85, 0/100), Tg, G′ and |η*| increased significantly when MMA was increased beyond 50%. Although the magnitude of Je0 asymptote was the same, it occurred at decreasing frequencies with increasing MMA. The J∞ increases linearly with T -Tg, but more so with polystyrene (PS) than with polymethyl methacrylate (PMMA). The |η*| showed non-Newtonian behavior at decreasing frequency with increasing MMA, the asymptotic form being consistent with Graessley models. The viscoelastic behavior can be correlated with chain flexibility and SMS triad concentration in copolymers. © 1979 Dr. Dietrich Steinkopff Verlag.