Experimental and Analytical Characterization of β-Tricalcium Phosphate Particle Reinforced Poly-L-Lactide Composites

Bioactive ceramics, β-tricalcium phosphate (β-TCP), particles reinforced bioabsorbable plastics poly-L lactide (PLLA) composites have been expected to apply for the fracture fixations which have more biocompatibility than monolithic PLLA. In this study, β-TCP/PLLA composites containing three different β-TCP contents (4.8, 9.5, 14.3wt%) were prepared by injection molding. The results of bending tests show bending strength decreases with increasing β-TCP contents. On the other hand, bending modulus increases with increasing β-TCP contents. After immersion tests in PBS at 37°C up to 8 weeks, the mechanical properties were hardly degraded in all specimens. The results of fracture surface observation by scanning electron microscopy indicated that microscopic damage such as debonding between β-TCP and PLLA initiates at β-TCP agglomeration and grows with increasing loading. Analytical predictions of the relationship between stress and strain based on micromechanics considering the progress of debonding between β-TCP and PLLA were in good agreement with experimental results.