ENHANCED INTERFACIAL ADHESION OF ULTRA-HIGH-MOLECULAR-WEIGHT POLYETHYLENE (UHMWPE) FIBERS BY OXYGEN PLASMA TREATMENT

Ultra-high molecular weight polyethylene (UHMWPE) fibers were subjecte d to oxygen plasma treatment in order to improve interfacial adhesion. The treated fibers were characterized by contact angle analysis, X-ra y photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) , atomic force microscopy (AFM), and mercury porosimetry. The surface free energy, O 1s/C 1s ratio, and surface area increased dramatically with 1 min treatment. However, as the treatment time increased further , these parameters either increased slowly at 30, 60, and 100 W, or de creased at 150 W. The increased surface free energy is attributed to t he polar component, while the increased O 1s/C 1s ratio is explained b y the oxygen-containing moieties introduced by the plasma treatment. T he oxygen plasma treatment also roughened the initially smooth surface of the UHMWPE fibers by forming micro-pores and thus increased the su rface area. The interfacial shear strength of UHMWPE fibers to vinyles ter resin was measured by micro-droplet tests and exhibited an increas ing trend, believed to result from the increased surface area, the sur face free energy and the oxygen-containing moieties due to the plasma treatment.