Influence of cure treatment on extent of reaction and glassy modulus for BADGE‐DDM epoxy resin

The extent of conversion of epoxy groups cured with diaminodiphenyl methane, a diamine, at 100°C was approximately 100%, and the glass‐transition temperature ( T   i g ) was found to be an increasing function of cure time with very large increases with extended postcure treatments at 180°C. However, this considerable increase in the T g with postcure at 180°C was not due to the reactions of epoxy and amine groups. The specific volume reduced with the T g to a minimum at 103° for the cured samples but showed a very slight increase with the T g for the postcured samples. It was also found that the glassy modulus ( E g ) was a linear decreasing function of the T g . There were two separate relationships between the E g and the rubbery modulus that depended on the cure conditions and suggested that the “structure” formed due to cure at a temperature of 100°C was different than that at postcure, which was 180°C. The most sensitive structural parameter for these cured epoxy resins was their T   i g . © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1265–1276, 2001