The correlation between cross-linking and thermal stability: Cross-linked polystyrenes and polymethacrylates

Cross-linked styrenes and methacrylates have been prepared by combining sty rene with divinylbenzene and methyl methacrylate with various dimethacrylat es. The gel contents and swelling ratios of these cross-linked copolymers h ave been measured and the materials have been analyzed by thermal analysis and a correlation was sought between cross-linking and thermal stability of the polymers. The cross-linked styrenes commence degradation at higher tem peratures than does polystyrene and significantly more char is produced. Fo r the cross-linked methacrylates the onset of degradation is actually earli er for the cross-linked polymers than for poly(methyl methacrylate) but aga in more char is obtained from the cross-linked polymers. (C) 1999 Elsevier Science Ltd. All rights reserved.