EFFECT OF TEMPERATURE AND MOISTURE ON THE IMPACT BEHAVIOR OF GRAPHITE-EPOXY COMPOSITES .1. IMPACT ENERGY-ABSORPTION

Dropped weight impact testing has been used to evaluate the influence of temperature and moisture on the impact resistance of unmodified and modified epoxy/graphite fiber composites. At ambient and low temperat ures, moisture was found to have little effect on damage initiation en ergy or subsequent energy absorption. At elevated temperature, the pre sence of moisture has a significant effect on damage initiation energy , with the change depending on the particular energy adsorption charac teristics of the matrix and the 'wet' epoxy phase glass transition tem perature. The energy required to initiate damage was found to decrease with temperature, and this is consistent with a reduction in matrix p roperties at elevated temperatures.