The Effect of Pressure on Moisture Diffusion in Polymer Matrix Composites

Abstract

Temperature and humidity play a significant role in the mechanical behavior and long-term durability of polymer matrix composites (PMCs). Several standard test methods including some accelerated test methods involving higher temperatures and pressures are available for environmental qualification of these PMCs. While the effect of temperature on humidity diffusion has been studied extensively, the effect of pressure has received less attention. This study seeks to interrogate the effect of pressure on diffusion. This effect was observed by building test chambers designed to maintain a constant relative humidity of 80 % at 60 • C at three different pressures (0.1014 MPa, 0.5171 MPa, and 1.0342 MPa). A liquid water immersion test chamber at 60 • C was also considered. It was observed that the time to saturation and the saturation moisture content increased with increasing chamber pressure. Immersion in liquid water provided the upper bound for the maximum moisture saturation and a lower bound for the time to saturation.

Diffusion Characteristics of Moisture in Polymer Composites under Different Hygrothermal Conditions

“…The pressure of the environment also affected the moisture diffusion behavior in PMCs. It was found that the time to saturation and the saturation moisture content increased with the pressure in the environmental chamber [12].…”

Dynamic humidity diffusion through the polyester/glass fibre composite

“…Furthermore, the flow velocity has an impact on the humidity absorption procedure: Davis et al [18] approved that the increase in the flow velocity causes an increment in the diffusion coefficient. As far as, Pilli et al[19] and Humeau et al [20] showed that the raise in the flow velocity induces the humidity diffusion phenomena acceleration. The research of Zhang et al [21] revealed that using the obtained regression equation, the temperature has a high influence on the diffusion process, especially for diffusion velocity.…”

A convection–diffusion porous media model for moisture transport in polymer composites: Model development and validation

“…Anomalous water diffusion through polymers were often reported, and water diffusion coefficients could be affected by many factors. These factors may include testing temperatures, glass transition temperature, moisture concentration, types of fillers, mechanical stress and pressure, polymer relaxation, and chemical interactions . Usually, Fickian models are too simple to fully model the complex moisture diffusion in polymers.…”