DIFFUSION-COEFFICIENTS OF POLYMERIC COMPOSITES SUBJECTED TO PERIODIC HYGROTHERMAL EXPOSURE

Diffusion coefficient is an important hygrothermal parameter used for theoretical estimation of moisture content in a body when exposed to a hygrothermal environment. The diffusion of moisture in a body involves a long time, continuous exposure in a climatic chamber. This may pose some practical difficulties, whereas a periodic exposure may be a feasible proposition. The present investigation is, therefore, aimed at determining diffusion coefficients for the continuous hygrothermal exposure from the data generated for the periodic exposure. The test results obtained from various types of glass-epoxy, glass-polyester, Kevlar-epoxy, and different combinations of Kevlar/carbon-epoxy composites are found to agree with available data, and the variation of diffusivity shows the desirable trend.