Imido-phenolic-triazine network polymers derived from maleimide-functionalnovolac

Polycyanate esters of an imide-modified novolac of different maleimide-cont ent were synthesised and characterised. The resins underwent a two-stage in dependent thermal curing through trimerisation of the cyanate groups as wel l as the addition polymerisation of the maleimide moieties. On heating, the cyanate esters were transformed to the imidophenolic-triazine network poly mers. The cured resins exhibited a higher initial decomposition temperature compared to the cured maleimide novolacs. Despite possessing higher crossl ink density, the imido phenolic triazines exhibited inferior thermal proper ties in comparison to a conventional phenolic-triazine resin. The presence of triazine crosslinks were found to disfavour the char forming reaction of the otherwise high-char yielding maleimide-novolac resins. Kinetics of the nonisothermal degradation revealed a lower activation energy for the pheno lic-triazine in contrast to the imido phenolic triazine which was kinetical ly compensated by a diminished frequency factor to give an overall decrease d rate of decomposition for the former. (C) 2000 Elsevier Science Ltd. All rights reserved.