International Journal of Thermophysics

, Volume 33, Issue 8, pp 1715-1725

First online:

The Effect of Pressure on Moisture Diffusion in Polymer Matrix Composites

  • S. P. PilliAffiliated withPacific Northwest National Laboratory Email author 
  • , L. V. SmithAffiliated withWashington State University

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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.


Acceleration Composites Humidity Moisture Relative humidity