Hydroxy‐terminated polybutadiene toughened epoxy resin: Chemical modification, microstructure, and impact strength

Abstract

Abstract The toughening of the epoxy resin diglycidyl ether of bisphenol A with hydroxy‐terminated polybutadiene (HTPB) was investigated. A chemical link between the elastomer and the epoxy resin was promoted employing tolylene diisocyanate (TDI). In the first step, HTPB and TDI (in excess) reacted forming urethane links, and after increasing the temperature and adding a catalyst, TDI–HTPB reacted with epoxy resin forming oxazolidone links. The reactions were followed by FTIR and chemical analysis. The final cured materials contained up to 10 phr of elastomer. Impact resistance increased with elastomer concentration up to 5 phr of HTPB, which was present as rubber particles with average diameter ranging from 1 to 4 μm. Higher concentrations of HTPB resulted in larger particles and gave lower impact values. The overall results have shown that it is possible to obtain, with the process employed, an impact resistance increase of 100% with the use of HTPB as a toughening agent for the epoxy resin. © 2002 John Wiley & Sons, Inc. Adv Polym Techn 21: 25–32, 2002; DOI 10.1002/adv.10012