Studies on the initiation of a free-radical condensation hybrid polymerization system

Compositions of hexamethoxymethyl melamine (HMMM)-ether polyol and acrylate can be cured by a hybrid polymerization comprising condensation polymeriza tion and free-radical polymerization, in the presence of a latent acid cata lyst at high temperature. It was found that the initiating free radical was derived from the decomposition of hydroperoxides, which was formed by the oxidation of active methylene groups catalyzed by HMMM. It was also found t hat strong acid could accelerate the free-radical polymerization in the hyb rid system. To make the formulations more flexible, the activities of diffe rent types of methylene groups were investigated and two compounds with mor e active methylene groups and hydroxyl were synthesized, characterized, and used as crosslinker-initiators in the hybrid polymerization system. (C) 20 00 John Wiley & Sons, Inc.