Tensile and water absorption properties of notched glass fiber/polypropylene and glass fiber/polyoxymethylene injection-molded composites

Abstract

In this work, the tensile properties and hydrothermal aging behavior of notched glass fiber/polypropylene (GF/PP) and glass fiber/polyoxymethylene (GF/POM) prepared by injection molding were investigated. It is shown that the notch strength ratio (NSR) of GF/PP was higher than that of GF/POM with the same fiber mass fraction. With the increase of the fiber mass fraction, the NSR decreased. After 30 times cyclic loading–unloading tensile process, the decrease rate of tensile strength was not evident at 55% level cyclic loading, whereas the decrease rate was over 15% when cyclic loading reached 85% level. The specimens were exposed to 80 °C hot water to investigate the hydrothermal aging behavior. For the water absorption properties, the weight gain and weight loss of GF/PP barely changed after 1600 h. The weight of GF/POM increased within 25 h, and then reached equilibrium. After 1600 h, the weight loss of GF/POM was below 0.4%. The effect of immersion time on the tensile strength of notched GF/POM was noticeable. The decrease rate of tensile strength of GF/POM reached 21% after 1600 h, owing to the hydrolysis of matrix and the weakened interface between matrix and glass fibers.