SHORT ARAMID-FIBER REINFORCED ULTRA-HIGH-MOLECULAR-WEIGHT POLYETHYLENE

Ultra-High Molecular Weight Polyethylene (UHMWPE) is frequently used i n artificial joints because of its high wear resistance. To extend the lifetime of these joints even further, it is necessary to decrease th e wear rate. The wear rate may be decreased by blending UHMWPE with sh ort aramid fibers. On account of the extremely high viscosity of UHMWP E mixing was accomplished by swirling the UHMWPE powder and the choppe d fibers with compressed dry nitrogen, and a composite with fairly uni formly distributed and randomly oriented fibers was obtained by compre ssion moulding. The failure behaviour of the composite changes from du ctile for low fiber content to brittle failure for higher fiber conten t. The deviation of the experimental Young's modulus from the theoreti cal value can be explained by, among others, the void content. Prelimi nary results show that the wear rate of UHMWPE indeed decreases with i ncorporation of the aramid fibers.