Study on Effects and Mechanism of PAA on Curing Reaction of Epoxy Resin Film

Liquid and solid epoxy resin were mixed.DDS was used as the curing agent and polyamic acid(PAA)was added to modify the resin matrix.Epoxy resin film was prepared using method of scraping membrane.The effects of solid-to-liquid ratio of epoxy and the amount of PAA on film forming ability,curing temperature and curing rate were studied by means of DSC,plate-wire-drawing method and FTIR.The reaction mechanism of PAA on the curing reaction of epoxy/DDS system was explored as well.The result showed that adding PAA into the resin matrix can improve the toughness of epoxy resin film,reduce the curing temperature and accelerate the curing rate.For this resin system(the mass ratio of solid epoxy to liquid epoxy was 50:50),while the amount of PAA was 5 wt%,the initial curing temperature was descended from 175.9 ℃to 138.8 ℃ and the gel time was descended from 162 min to 46 min.The resin system was turned from high temperature system into nearly medium temperature system.