PNNL

Abstract

Moisture plays a significant role in influencing the mechanical behavior and long-term durability of composites. This paper aims to understand the basic concepts of moisture transport in polymeric composites at a fundamental level. Moisture uptake in two different composite material systems, a simple toughened epoxy laminated system and a more complex toughened epoxy random fiber system, is analyzed using the standard ASTM test methodology. Hygrothermal humidity chamber, at 85% RH and 60°C, is used in combination with D2O water to subsequently characterize the diffusion of D2O using Nuclear Reaction Analysis (NRA) from Ion Accelerator Beam Lines and end stations. Moisture content is measured as a function of through thickness depth using NRA. A set of parallel experiments using a novel accelerated technique is done on the same set of materials. Accelerated test setup uses similar test conditions of 85% RH and 60°C except for higher pressures of ~65 psi. Acceleration of moisture ingression is obtained by increasing the pressure in the test chamber. Results from standard and accelerated humidity tests are compared with an eventual goal to develop an accelerated composite moisture infusion test methodology and characterization for nearly any fiber-reinforced composite material.