Preparation of poly(lactic acid) composites containing calcium carbonate (vaterite)

A new type of ceramic-polymer biomaterial having excellent apatite-forming ability in simulated body fluid was prepared by hot-pressing a mixture of poly(-L-lactic acid) (PLA) and calcium carbonate (vaterite). After PLA dissolved in methylene chloride was mixed with calcium carbonate consisting of vaterite, the mixture was dried completely and subsequently hot-pressed uniaxially under a pressure of 40 MPa at 180 degrees C. When 30 wt% vaterite was introduced, the modulus of elasticity was effectively improved by 3.5-6 GPa, which was about twice higher than the modulus of PLA. The composite showed no brittle fracture behavior and a comparably high bending strength of approximately 50 MPa. The composite containing 30 wt% vaterite formed a 5-15-microm-thick bonelike apatite layer on its surface after soaking in SBF at 37 degrees C even for 1-3d.