EFFECT OF WATER-ABSORPTION ON THE IZOD IMPACT ENERGY OF CROSS-LINKED POLY(METHYL METHACRYLATE-ACRYLIC ACID) AND THEIR COMPOSITES

Crosslinked poly(methyl methacrylate-acrylic acid) and composites usin g this crosslinked copolymer as the matrix have been synthesized and e valuated for their potential as bioimplantable materials in design of a new class of bone anchors. The low-velocity impact energy absorption properties of this slightly hydrophilic class of materials were exami ned by Izod impact testing. In particular, the influence of swelling ( by absorption of water) on the impact resistance of the crosslinked co polymer and composites based on this copolymer was investigated. Also, the influence of fiber type and preform architecture on the impact re sistance of the composite, in both the dry and swollen states, was inv estigated. The fracture surfaces and the modes of failure in these tes ts were examined using scanning electron microscopy. The results indic ated that absorption of water leads to about a threefold increase in t he impact resistance of the copolymer. However, the increase in the im pact resistance of the composite samples after water absorption varied considerably, depending on the type and form of fibrous reinforcement . These results and our understanding of the role of water absorption on the impact resistance of these novel systems are presented.