Thermal analysis of solution copolymers of styrene with N-phenylmaleimide

Free-radical-initiated copolymerization of N-phenylmaleimide (NPMI) with st yrene (St) at 110 degreesC in a toluene solution initiated by AIBN was carr ied out by a semibatch method. The compositions of the copolymers were dete rmined by using an elemental analyzer. The glass-transition temperatures of the copolymers were measured by differential scanning calorimetry. All the semibatch copolymers show a single glass-transition temperature that incre ases markedly with increasing NPMI content in the copolymers. The thermal s tabilities of the copolymers were studied by using a programmed thermogravi metric analysis technique. Copolymers show a considerable increase in therm al stability and different degradation reaction mechanisms with increasing content of NPMI. (C) 2002 John Wiley & Sons, Inc.