Abstract: A latent and mediumtemperature cured epoxy resin system was prepared from epoxy/ micronizeddicyandiamide/FH1. Polarizing microscope revealed that the micronized dicyandiamide could be welldistributed and kept stable in epoxy. The initial curing temperature was decreased about 40~50 ℃compared with that based on nonmicronizeddicyandiamide. The optimal mechanical properties of the resin were flexural strength 56.3 kJ/m2, tensile strength 91.4 MPa, elongation at break 4.6%. For the composites reinforced with fiberglass, the retention rate of mechanical properties at wetting condition was over 70 %.

Key words: micronized dicyandiamide, prepreg, toughness, hot-wet mechanical property