Cure reactions of epoxy/anhydride/(polyamide copolymer) blends

The cure kinetics of blends of epoxy (DGEBA, diglycidyl ether of bisphenol A)/anhydride resin with polyamide copolymer, poly(dimmer acid-co-alkyl polyamine), were studied using differential scanning calorimetry (DSC)|under isothermal condition. On increasing the amount of polyamide copolymer in the blends, the reaction rate was increased and the final cure conversion was decreased. Lower values of final cure conversions in the epoxy/ (polyamide copolymer)|blends indicate that polyamide hinders the cure reaction between the epoxy and the curing agent. The value of the reaction order, m, for the initial autocatalytic reaction was not affected by blending polyamide copolymer with epoxy resin, and the value was approximately 1.3, whereas the reaction order,n, for the generaln-th order of reaction was increased by increasing the amount of polyamide copolymer in the blends, and the value increased from 1.6 to 4.0. A diffusion-controlled reaction was observed as the cure conversion increased and the rate equation was successfully analyzed by incorporating the diffusion control term for the epoxy/anhydride/(polyamide copolymer)|blends. Complete miscibility was observed in the uncured blends of epoxy/(polyamide copolymer)|up to 120°C, but phase separations occurred in the early stages of the curing process at higher temperatures than 120°C. During the curing process, the cure reaction involving the functional group in polyamide copolymer was detected on a DSC thermogram.