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 degreesC was approximately 100%, and the glass-transiti on temperature (T-g(i)) was found to be an increasing function of cure time with very large increases with extended postcure treatments at 180 degrees C. However, this considerable increase in the T-g with postcure at 180 degr eesC was not due to the reactions of epoxy and amine groups. The specific v olume reduced with the T-g to a minimum at 103 degrees for the cured sample s 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 fu nction of the T-g. There were two separate relationships between the E-g an d the rubbery modulus that depended on the cure conditions and suggested th at the "structure" formed due to cure at a temperature of 100 degreesC was different than that at postcure, which was 180'C. The most sensitive struct ural parameter for these cured epoxy resins was their T-g(i) (C) 20012001 J ohn Wiley & Sons, Inc.