PNNL

Abstract

ABSTRACT: Moisture plays a significant role in influencing the mechanical behavior and long-term durability of composites. With the current available testing techniques the time required for environmental qualification of polymer composites can be on the order of several years and any interruption in the test can result in a significant cost and schedule penalty. Because of these long environmental conditioning times there is a strong desire to accelerate the process to advance environmental qualification of potential candidate materials for use in commercial and military aerospace structures. An accelerated humidity test technique is developed where acceleration of moisture ingression is obtained by increasing the pressure in the test chamber. A hygrothermal humidity chamber is used in combination with D2O water to subsequently characterize the diffusion of D2O using Nuclear Reaction Analysis (NRA). Moisture content is also measured as a function of through thickness depth using NRA. The accelerated technique has shown to increase the diffusivity of the material forms tested on the order of 80% as compared to conventional, static hot-wet exposed samples. A comparison of experimental data to traditional Fick’s law diffusion models is in relatively good agreement for the materials and conditions tested.