Improved adhesion properties of poly-p-phenyleneterephthamide fibers with a rubber matrix via UV-initiated grafting modification

In this research, ultraviolet (UV) irradiation induced graft polymerization of glycidyl methacrylate (GMA) was performed to modify the surface properties of poly-p-phenyleneterephthamide (PPTA) fibers. The improvement of adhesion with a rubber matrix was achieved due to the introduction of epoxy groups. The successful grafting of GMA on the PPTA fiber surface was ascertained by characterization using X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy (SEM). The tensile properties of PPTA fibers after each stage of surface modification were determined by tensile testing of single-filaments. A single-fiber pull-out test was applied to evaluate the adhesion of PPTA fibers with the rubber matrix. The pull-out force of grafted PPTA fibers exceeded that of the pristine fibers by 53.7%. Resorcinol-formaldehyde-latex (RFL) dipping was applied to further improve the adhesion properties. As a result, the fibers with GMA grafting followed by RFL dipping exhibited a 80.8% improvement compared with the pristine fibers and achieved much higher adhesion strength with rubber matrix, compared to the PPTA fibers modified with conventional industrial method of isocyanate (NCO) and RFL two bath dipping.