The relationship between polymerization reaction kinetics and the optimum physical properties and processing of epoxy-based encapsulating systems

The effect of controlled polymerization reaction kinetics on the thermal and mechanical properties before and after gelation was studied. The modulus and thermal expansion coefficient below T/sub g/ of the fully curved epoxy were achieved during the gelation process. Moisture absorption was reduced and the glass transition temperature raised only after increasing the crosslink density of the resin system through completion of the reaction via post cure. After gelation, a high extent of cure was achieved in 12 minutes or less at the vendor´s recommended cure temperature, regardless of the temperature at gelation. Extended cure profiles do not appear to be necessary to achieve the desirable properties of the fully cured resin. The properties studied were dependent only upon the extent of cure and not on the actual cure temperature path profile.<>