Adjusting the measured weight loss of aged graphite fabric/PMR-15 composites

The purposes of this study is to evaluate the growth of the surface damage layer in polymer matrix composites (PMC's) fabricated with graphite fabric reinforcement and to determine the effects of the cut-surface degradation on the overall thermo-oxidative (TOS) stability of these materials. Four important conclusions were made about the TOS behavior of T650-35/PMR-15 fabric-reinforced composites: 1) Three stages of composite weight loss were seen on the plot of weight loss versus aging time; 2) the depth of the cut-edge damage is related to the composite thickness; 3) the actual weight loss realized by a mechanical test specimen that has had all the aging-induced cut-edge damage removed during the preparation process is significantly less than the weight loss measured using specimens with a high percentage of cut edges exposed to the damaging environment; and 4) an extrapolation of a section of the weight loss curve can be used to obtain a more correct estimate of the actual weight loss after extended periods of aging at elevated temperatures.