International Journal of Thermophysics

, Volume 33, Issue 8, pp 1715–1725

The Effect of Pressure on Moisture Diffusion in Polymer Matrix Composites

Article

DOI: 10.1007/s10765-012-1329-3

Cite this article as:
Pilli, S.P. & Smith, L.V. Int J Thermophys (2012) 33: 1715. doi:10.1007/s10765-012-1329-3

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.

Keywords

Acceleration Composites Humidity Moisture Relative humidity 

List of Symbols

C

Moisture concentration

D

Diffusivity (mass diffusion coefficient)

Db

Bulk diffusivity

dv

Humidity density

\({\phi}\)

Relative humidity

h

Thickness of test specimen

K

Material constant

Mda

Mass of dry air

Mw

Mass of water vapor

p

Pressure

T

Temperature

t

Time

Tg

Glass-transition temperature of the composite

tm

Time to reach 99.9 % moisture saturation

v

Specific volume of moist air mixture

V

Total volume of the sample

W

Absolute humidity

xw

Mole fraction of water vapor

xws

Saturated mole fraction of water vapor

Copyright information

© Springer Science + Business Media New York 2012

Authors and Affiliations

  1. 1.Pacific Northwest National LaboratoryRichlandUSA
  2. 2.Washington State UniversityPullmanUSA

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