THERMAL-DEGRADATION OF POLY(METHYL METHACRYLATE) POLY-4-BROMOSTYRENE BLENDS AND METHYL-METHACRYLATE 4-BROMOSTYRENE COPOLYMERS

The thermal degradation behaviour of poly-4-bromostyrene (PBrS), a blend of PBrS with poly(methyl methacrylate) (PMMA) and a copolymer of BrS and MMA has been studied using thermogravimetry, differential thermal analysis and thermal volatilisation analysis (TVA). The condensable volatile products from the TVA experiments have been subjected to initial separation by subambient TVA and the less volatile liquids have been further examined by GCMS. The cold ring fraction of products volatile at degradation temperature but not at ambient temperatures has also been characterised. The degradation behaviour of PBrS has been found to be closely analogous to that of polystyrene. A blend of PBrS and PMMA, however, unlike the corresponding polystyrene-PMMA blend, showed some interaction during degradation, resulting in some stabilisation of the PBrS. The copolymer of BrS and MMA behaved upon degradation rather like PBrS. In all these experiments, the major products were the monomers, accompanied (in contrast to the behaviour of PMMA) by a significant cold ring fraction: for blend and copolymer, this contained both types of repeat unit. A mechanism of interaction has been suggested.