EMULSION COPOLYMERIZATION OF N-PHENYLMALEIMIDE WITH STYRENE

Emulsion copolymerization of N-phenylmaleimide (PMI) with styrene (St) was conducted via semibatch and batch methods. The effect of monomer mixture composition and method of copolymerization on copolymer struct ure-property relationships was investigated. The semibatch copolymers have a homogeneous molecular structure, exhibiting a single T-g which increases linearly with increasing PMI content. The batch copolymers h ave a heterogeneous molecular structure, exhibiting two T-g's, assigne d to the polystyrene (PSt) and poly(PMI-co-St) components. The composi tion drift in the batch-copolymerized product, at different conversion levels, was examined by DSC and FTIR techniques. In general, the inhe rent viscosity of the semibatch copolymers is lower than that of the c orresponding batch ones. The Young's modulus increases for the semibat ch copolymers, with increasing PMI content, while a clear trend for th e batch copolymers is not found. The tensile strength tends to decreas e for both types of copolymers when PMI content increases. The thermal stability increases with increasing PMI content in the copolymers. (C ) 1996 John Wiley & Sons,Inc.