Tensile behavior of thermoplastic composites including temperature, moisture, and hygrothermal effects

An experimental study was conducted to investigate the effect of temperature, moisture, and hygrothermal aging on the tensile behavior of thermoplastic composites. Four different composites including talc filled and short glass fiber reinforced polypropylene, short glass fiber reinforced polyamide-6.6, and a blend of polyphenylene ether and polystyrene with short glass fibers were used for the study. Kinetics of water absorption and desorption were investigated for polyamide-6.6 composites and Fickian behavior was observed. The reductions in tensile strength and elastic modulus due to water absorption are represented by mathematical relations as a function of moisture content. In addition to moisture content, aging time was also found to influence the tensile behavior. A parameter is introduced for correlation of normalized stiffness and strength with different aging times and temperatures. Higher strength and stiffness obtained for re-dried samples after aging was explained by an increase in crystallinity.