Determination of Epoxy/Anhydride Mixing Ratio for the Highly Silica Filled Compounds with Chromium (III) Octoate Catalyst

In this study, epoxy/anhydride mixing ratio for the highly silica filled compounds with chromium (III) octoate catalyst was investigated at a low curing temperature (71°C for 40 hr) by evaluating the compressive strength with the weight ratio ranges from 0.3/1.0 to 1.0/1.0 of epoxy part (Part A)/anhydride part (Part B). In case of epoxy/anhydride com- pounds used surface unmodified silica by coupling agent, these compounds need excess anhydride unlike the weight ratio in the conventional epoxy/anhydride compounds. In curing behavior, the epoxy/anhydride compounds containing chromium (III) octoate showed high conversions at 71°C for 40 hr, even if a dipropylene glycol (DPG) was not used as a poly- merization initiator. Also, DPG leads to a poor epoxy network structure. In conclusion, the appropriate weight ratio of Part A/Part B of highly silica filled epoxy/anhydride compounds with chromium (III) octoate catalyst is 0.5/1.0 and the max- imum amounts of silica is 1470 phr of epoxy resin.