Moisture Diffusion in Fiber Reinforced Plastics

Fiber-reinforced epoxy laminates were exposed to several combinations of temperature and relative humidity. The purpose was to determine rates and extent of moisture absorption. Diffusion rates varied with temperature, and equilibrium moisture contents varied with relative humidity. Data analysis provided values for the material properties that determined diffusion behavior. A nonlinear diffusion model containing these values was shown to describe and predict absorption behavior for any combination of temperature and humidity. The model also describes desorption and correlates well with experimental data from changing humidity conditions.