Styrene‐maleic anhydride copolymers: Synthesis, characterization, and thermal properties

Radical copolymerization of styrene and maleic anhydride have been carried out in N, N-dimethylformamide at 60°C using 2,2′-azobisisobutyronitrile as initiator. The copolymer compositions were determined using an aqueous conductometric direct titration method. Monomer reactivity ratios were calculated by Fineman-Ross, Kelen-Tudos, and conversion-based Kelen-Tudos methods. Gel permeation chromatography was used to determine molecular weights and polydispersity indexes. The thermal degradation and energy of activation of the degradation process were determined by several thermogravimetric analysis and differential scanning calorimetric models. The thermal degradation of the copolymer is a two-stage process, the major degradation being the second stage. The copolymer degrades at a lower temperature than polystyrene. © 1996 John Wiley & Sons, Inc.