Effect of quercetin on the structure and oxidation resistance of polyphenylene sulfide fiber prepared by melt spinning

Polyphenylene sulfide fiber is easily oxidized at high temperature, thus vastly reducing its application range. In this study, polyphenylene sulfide/quercetin fibers were prepared via melt spinning. The effect of quercetin on the spinnability of the composite fibers was explored, and their cross-sectional morphology, crystalline properties, orientation, tensile properties, thermal stability and oxidation stability were investigated. At the quercetin content of 1.5 wt.%, particle agglomerates and some gasification, causing fluctuations in melt pressure, fiber breakage and poor spinnability, were observed in the polyphenylene sulfide matrix. The addition of quercetin can increase the crystallization temperature of polyphenylene sulfide, shorten its crystallization time, refine the crystalline particles therein, and improve the degree of fiber orientation. At the quercetin content of 1.0 wt.%, the tensile strength and elongation at break of composite fibers increased by 30.8% and 7.6%, respectively, as compared to those of pure polyphenylene sulfide fibers. Moreover, the decomposition temperature and the oxidation induction temperature at a 5% weight loss were 16.3 degrees C and 13.4 degrees C higher than those of the unmodified PPS fibers. The loss of strength of composite fibers subjected to oxidation for 240 h was only 18.4%. The X-ray diffraction results showed that the phenolic hydroxyl groups in the quercetin structure were able to capture free radicals generated during the oxidation of polyphenylene sulfide fibers, as well as inhibit the oxidative degradation reaction and improve the oxidative stability of the fiber. The oxidation resistance mechanism of composite fibers was also proposed.