Thermal degradation of poly(tertbutyl aziridine) poly(methyl methacrylate) graft copolymer

The degradation behaviour of a high molecular weight PMMA sample in which approximately 2% of the MMA units have been modified and grafted with PTBA chains of molecular weight 5000, to give a product containing about 50% by weight of PTBA, has been investigated. The techniques used were the same as in recently reported investigations of PTBA, PTBA-PMMA block copolymer and poly(N-methyl-N-tertbutyl-aminoethyl methacrylate) (PMTBAEM), and included TG, DTA and thermal volatilisation analysis (TVA). Products from the TVA experiments were separated and characterised. The graft copolymer is less stable than PMMA and comparable in stability to PTBA. It appears that the grafted side chains degrade primarily to PTBA-related oligomeric material, accompanied by a small proportion of volatile products also derived from the PTBA chains, whereas the main backbone gives predominantly MMA monomer. (C) 1997 Elsevier Science Limited.