INFLUENCE OF TEMPERATURE AND HYDROSTATIC-PRESSURE ON MOISTURE ABSORPTION IN POLYMER RESINS

Polyester resins are widely used as the matrix in glass fibre-reinforced polymer composites. Moisture absorption has an adverse effect on their mechanical properties. Examination of two cured unsaturated polymers, Stypol R1067/32 and R1067/26, at various temperatures and hydrostatic pressures has shown that the saturation level of moisture in R1067/26 is independent of both temperature and pressure, but in R1067/32 at 5-degrees-C the level depended on pressure. The temperature dependences of the diffusivities were found to be well described by Arrhenius expressions. The diffusivities were found to decrease slightly with increasing pressure, the effect being largest at the highest temperature, in qualitative agreement with theories based on changes in the free volumes in the polymers.