Benzimidazole derivatives and their complexes as accelerators for curing of epoxy resin

Bisphenol-A-based epoxy resin was cured with an anhydride hardener in the presence of benzimidazoles and their complexes as accelerators. Investigations have revealed an appreciable reduction in the cure and gel times. The kinetic studies based on DSC showed that the rate of curing increases with enhanced concentration of accelerators. The coefficient of thermal expansion has been reduced considerably in the presence of the benzimidazole. The electrical properties of the cured epoxy resin system were unaffected by lower concentrations of benzimidazoles. A mechanism for curing has been proposed with 1,3-bis(2-benzimidazolyl)benzene as accelerator based on IR studies, which indicate the involvement of the secondary and tertiary nitrogen of the benzimidazole in the crosslinking of the resin system. © 2008 Wiley Periodicals, Inc