SYNTHESIS AND PROPERTIES OF EPOXY-EPISULFIDE RESINS

Standard epoxy resins have good mechanical properties, bur their prolo nged low temperature curing time limits their potential use in clinica l applications as well as in many industrial applications. A fast-curi ng epoxy-episulfide resin has been developed. The gel time of epoxy-ep isulfide made from EPON(R) 828 ranges from 2 to 10 minutes by changing the ratio of the ingredients. The heat of reaction of this system is low, resulting in low cure shrinkage. Water absorption of the episulfi de network is low. The epoxy-episulfide system cured with polyamide cu ring agent V-40(R) exhibits two transition temperatures, at about 85 d egrees C and 130 degrees C, as shown in dynamic mechanical analysis da ta. In order to solve the long term stability problem of the above epi sulfides, and also the mixing problem, a lower viscosity resin, Eponex (R), was used to make Eponex-sulfide. Eponex-sulfide systems show prom ise in that they remain in a stable liquid form without epoxy. The oth er advantages appear to be retained.