Surface Modification Of UHMEPE Fibers For Enhancing The Interfacial Properties Of Fibers/Rubber Composites

The ultra-high molecular weight polyethylene (UHMWPE) fiber has remarkable characteristics of resistance to impact and corrosion, low density, high tensile strength. However, one major drawback of UHMWPE fibers is its poor interfacial properties due to its inert and smooth surface. This deficiency primarily limits its scope of application for composite. In this research, the glycidyl methacrylate (GMA) was grafted onto the surface of ultra-high molecular weight polyethylene (UHMWPE) by ultraviolet (UV) technology, to enhance the interfacial property of UHMWPE fibers/rubber composites.Firstly, the technological conditions of reaction vessel, solvent, and monomer concentration for UV grafting were investigated. The UV spectrophotometer was used to detect the UV transmittance. The results show that the tube used in the laboratory has better transmittance at the wavelength of 360 nm and can be used for reaction vessel. The water, acetone, n-heptane, methanol was used as the solvent for UV grafting. Fourier transform infrared spectroscopy (FTIR) was employed to characterize the chemical bonding on the surface of the UHMWPE fibers. The FTIR spectrum shows that the absorption peaks of ester groups and epoxy groups were found on the fibers surface when the methanol was used as the solvent. The modified fibers were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM). XPS and SEM results revealed that GMA was grafted onto the fibers successfully. The interfacial property of fibers to rubber matrix were characterized by H pull-out testing, and it showed that the maximum force was increased by 16%(from 34.1 N to 39.7 N) compared with that of the untreated fibers.Further, the technology of ozone treatment and UV grafting was investigated. The fibers were first pre-treated by ozone to introduce oxygen-functional groups. The grafting polymerization of glycidyl methacrylate (GMA) onto the ozone treated fibers was implemented by UV irradiation. The effect of grafting time and monomer concentration were investigated. The modified fibers were characterized by XPS, FTIR, and SEM. The results revealed that a compact and even PGMA was grafted onto the fibers successfully. The ozone-pretreatment was used not only for physical etching of fiber surface, but also for formation of active site. The H pull-out testing showed that the maximum force was increased by 79%(from 34.1 N to 61.0 N) compared with that of the untreated fibers.Finally, the effect of ferrous ion on the ozone-UV grafting was studied. It can be dramatically enhanced the adhesion property by the addition of benzophenone and ferrous ion in the GMA solution. The H pull-out testing showed that the maximum force was increased by 145% (from 34.1 N to 83.7 N) compared with that of the untreated fibers.