Mechanical Properties of .BETA.-Tricalcium Phosphate/Polylactic Acid Composites Prepared through Ball-Milling

Ball milling after stirring of the starting materials in the preparation of the beta-tricalcium phosphate (TCP)/polylactic acid (PLA) composites was attempted. The effect of ball-milling time on the mechanical properties of the composites was examined. A slurry was prepared from beta-TCP and PLA with a molecular weight of 120000 to 200000 in a mass ratio of 75:25. This was ball-milled at ambient temperature for periods up to 48 h, and then hot-pressed to form dense composites. The mechanical properties of the composites were evaluated using a three-point bending test. The bending strength of the composites increased with increasing ball-milling time and decreased with increasing molecular weight of the PLA. Composites prepared from PLA with a molecular weight of 120000 that were ball-milled for 48 h showed a mechanical strength of 80 MPa, which is nearly equal to that of human cortical bone. The increase in bending strength is attributed to a decrease in the size of the beta-TCP aggregates due to ball milling. 20 refs.