Moisture sorption effects on carbon fiber-reinforced phenylethynl-terminated Ultem™ composites

High-performance aerospace applications require materials that are able to withstand exposure to extreme temperatures, high relative humidities, solvents, and other chemicals. Due to their high-performance thermal and mechanical characteristics, poly(etherimide)s are bring implemented in such applications. Prior to such use, environmental effects on material performance must be understood. In this study, the effects of moisture sorption on the mechanical properties of carbon-fiber-reinforced phenylethynyl-terminated poly(etherimide) matrix composites were investigated. The through-the-thickness moisture diffusion coefficient and the maximum moisture equilibrium content were determined for the unidirectional composites for exposure to 90 degreesC and 85% relative humidity. In addition, the composites were tested for retention of transverse flexural strength and apparent interlaminar shear strength at maximum moisture equilibrium content. The same properties were tested for property retention following desorption of moisture to a 90 degreesC, 2% relative humidity moisture content. The composite showed high mechanical property retention with recoverable matrix plasticization being the source of property reductions.