PLASMA-TREATED ULTRA-HIGH STRENGTH POLYETHYLENE FIBERS .2. INCREASED ADHESION TO POLY(METHYL METHACRYLATE)

The use of ultra-high strength polyethylene (UHSPE) fibers in composites has been limited by problems with adhesion to the matrix. The present study presents a gas plasma treatment of UHSPE fibers (Spectra(TM) 900 and 1000) to improve adhesion with poly(methyl methacrylate) bone cements. The gases used were nitrogen, argon, and carbon dioxide for treatment times of 0, 1, 5, and 10 min. Significant improvements in the interfacial shear strength and fiber pull-out energies were achieved with only modest changes in the tensile strengths. Increased adhesion was attributed to improved wettability of the fiber surface. Increased fiber pull-out energies were attributed to enhanced propensity for surface peeling causing higher forces needed for fiber pull-out, based on SEM photomicrographs and fiber pull-out curves. No significant differences in interfacial shear strengths and energies were observed among fibers exposed to the three gases. One-minute exposure times were sufficient to cause significant improvements in adhesion.