Class-transition temperature-conversion relationship for an epoxy-hexahydro-4-methylphthalic anhydride system

The DGEBA-MHHPA epoxy system has found increasing applications in microelec tronics packaging, making crucial the ability to understand and model the c ure kinetics mechanism accurately. The present article reports on work done to elucidate an appropriate model, modified from the empirical DiBenedetto 's equation, to relate the glass-transition temperature (T-g) to the degree of conversion for a DGEBA-MHHPA epoxy system. This model employs the ratio of segmental mobility for crosslinked and uncrosslinked polymers, lambda, to fit the model curve to the data obtained. A higher ratio value was shown to indicate a more consistent rate of increase of T-g in relation to the d egree of conversion, while a lower value indicated that the rate of T-g inc rease was disproportionately higher at higher degrees of conversion. The be st fit value of lambda determined by regression analysis for the DGEBA-MHHP A epoxy system was 0.64, which appeared to be higher than for those previou sly obtained for other epoxy systems, which ranged from 0.43-0.58. The high est T-g value obtained experimentally, T-g max, was 146 degrees C, which is significantly below the derived theoretical maximum T-g infinity value of 170. (C) 2000 John Wiley & Sons, Inc.