MISCIBILITY BEHAVIOR OF POLY(STYRENE-CO-N-MALEIMIDE)S WITH POLY(METHYL METHACRYLATE)

Various maleimide-containing copolymers have been studied with respect to their miscibility behaviour towards poly(methyl methacrylate) (PMM A) by differential scanning calorimetry (d.s.c.). Poly(styrene-co-N-ma leimide)s (NMIs) with maleimide contents between 8 and 21 wt% were sho wn to be completely miscible with PMMA, whereas a blend containing 45 wt% maleimide in the NMI was not miscible with PMMA. In contrast to th e miscible blend NMI-21/PMMA, a NMI-21-MMA polymer containing 21 wt% m aleimide, 40 wt% methyl methacrylate, 35 wt% styrene and 4 wt% maleic anhydride proved to be immiscible with PMMA. By means of d.s.c. and Fo urier transform infra-red spectroscopy measurements on the polymer ble nds and their model compounds, it was possible to account for the misc ibility behaviour in terms of competing equilibria and concentration e ffects.