Studies on Cure kinetics and Rheological Properties of Epoxy/Polyurethane Blend System

에폭시/폴리우레탄 블렌드계의 강화 동력학 및 유변학적 특성에 관한 연구

The effects of composition ratios of epoxy resin (EP) and polyurethane (PU) blends on cure kinetics and reheological properties were investigated. In this work, 20 phr of DDM (4,4'- diamino diphenyl methane) was used as a curing agent for epoxy resin. And the composition of EP/PU was varied within 100/0∼100/40 phr. The cure activation energies ($E_{a}$), which were obtained from dynamic DSC data by Kissinger method, were increased in 40 phr of PU in EP than in pure EP. The rheological properties of blend system were investigated under isothermal condition using a rheometer. Crosslinking activation energies ($E_{c}$) were also determined from the Arrhenius equation based on gel time and curing temperature. As a result, both gelaton time and crosslinking activation energy increased with increasling the content of PU. These results could be explained by the increase in reactivity between the hydroxyl group in EP and isocyanate group in PU, resulting in an increase in the crosslinking density.