Predicting hygrothermal degradation of composites in accelerated testing

Abstract

Advanced fiber reinforced polymer (FRP) composite materials have been increasingly used in many applications relevant to the Army’s transformation. Many of these applications require the FRP composites to perform over long periods in harsh environments with extremes of temperature, humidity, water, and exposure to ultraviolet radiation and chemicals. It is important to understand the long term durability of FRP composites to environmental stimuli. This paper presents results of the hygrothermal degradation of E-glass/epoxy composites in accelerated tests and compares these results to predictions made using a modeling methodology based on Arrhenius-type reaction laws. To investigate the hygrothermal degradation behavior, E-glass/epoxy composites were subjected to accelerated tests at controlled temperatures and relative humidities. The specimens were exposed in an unloaded state and with a static tensile load of 2% of the ultimate transverse tensile strength. In the model predictions, three degradation mechanisms were considered: (1) post-curing, (2) thermal degradation, and (3) hygrothermal degradation.