A study of crosslinking of diglycidylether of bisphenol A (DGEBA) by four copolymers of poly(acrylic acid-co-styrene) having different acid group percentages, in the range 7.6-76.6%, was done by FTIR. The study was done in the isothermal mode for four different temperatures, the reaction being accelerated by triethylamine. We followed each by temperature and the variation of the area of the epoxy infrared band (912-916 cm(-1)) versus time. The results showed that the mechanism was complex and depended on the acid composition in the copolymer. Three types of reaction were involved: addition esterification, etherification, and condensation esterification. (C) 2003 Wiley Periodicals, Inc.