Effects of curing accelerators on physical properties of epoxy molding compound (EMC)

Abstract

AbstractThe effects of various curing accelerators on the physical properties of epoxy molding compounds (EMCs) were investigated. Such properties as elasticities in rubbery and glassy regions, glass transition temperature, thermal expansion coefficient, and water absorption at 60°C of neat epoxy resins using various curing accelerators were found to be directly reflected in the properties of the EMCs that were prepared by using each resin system. However, volume resistivity and saturated water absorption at 120°C were not reflected. This was attributed to differences in the catalytic reactivity of accelerators causing different melt viscosity for the EMC, which resulted in different densities (packing degrees) and affected physical properties of molded EMC. On the other hand, it was found that the density of molded EMC was also affected by the molding conditions. To improve the physical properties of the molded EMC, in addition to proper selection of accelerators, it was very important to set the melt viscosity of the EMC as high as possible within the moldable range and to select suitable molding conditions.