Novel dibutyltin oxide-tributyl phosphate condensate as accelerator for the curing of the epoxy resin/4,4 '-diamino diphenyl sulfone system. I. Chemical reactions and properties of the cured resin

A crystalline condensate of dibutyltin oxide and tributyl phosphate (Sn-P-c ) was more effective than the stannous octoate and dibutyltin dilaurate in accelerating the curing of the epoxy resin/4,4'-diamino diphenyl sulfone (D DS) system, based on an equal tin concentration. Water took part in the rea ction and played an important role in the morphology and mechanical propert ies of the cured resin when Sn-P-c was used as the accelerator. In the pres ence of Sn-P-c, water first reacted with glycidyl ether to yield glycerol e ther; the yielded hydroxyl group may further catalyze the amino/epoxy group reaction. In the absence of water or polar hydroxyl additives, Sn-P-c did not completely dissolve in the resin systems, and the cured resin was trans lucent material with poor mechanical strength. In the presence of a small a mount of water, the cured material became transparent. Both flexural streng th and maximum deflection were increased greatly. (C) 2001 John Wiley & Son s, Inc.