Preparation of polylactic acid composites containing β–Ca(PO₃)₂ fibers

Novel biomaterials for application to artificial bone with modulus of elasticity close to that of natural bone were prepared using bioresorbable poly-L-lactic acid (PLLA) and high-strength β–Ca(PO₃)₂ fibers treated with dilute NaOH solution. PLLA dissolved by using methylene chloride was mixed with the fibers. After drying the mixture, it was hot-pressed uniaxially under a pressure of 40 MPa at 180 °C, resulting in fabrication of a PLLA composite containing β–Ca(PO₃)₂ fibers. Almost no degradation in the bending strength was observed even when a large amount of the fibers (≈50 wt. %) was introduced, and the modulus of elasticity was increased effectively with increasing the fiber content. The PLLA composite with modulus of elasticity of <5 GPa similar to that of natural bone was found to be prepared when the fiber content was over 35 wt. %. The bending test of the composites showed that very high energy is consumed for their fracture and that the fracture proceeds step by step, even beyond the maximum stress.