Thermal and Mechanical Properties of Epoxy/SiC Composites Degraded by Moisture and Temperature

摘要

The amount of degradation that takes place in a polymer composite is related directly to the quantity of moisture it absorbs. Other factors, as temperature and oxygen concentration, can also modify the mechanical properties. Plastification and swelling are among the undesirable consequences of absorbed water. The aim of this work is to investigate the effect of moisture on mechanical properties of epoxy reinforced with silicon carbide. Two different SiC sizes (nano and 10 μm) were studied. In order to quantify the degradation of the composite, the specimens were exposed to three environments (95% RH-relative humidity-and 60 °C, 95% RH and RT-room temperature, and 5% RH and 60 °C). Variations of T_g (glass transition temperature), water uptake and mechanical properties were determined as a function of exposure time. Thermal conductivity was evaluated in pristine material and after 31 days in the three environments (30 days in the ageing environment and 24 h of stabilization in a desiccator).