Effect of HA with different grain size range on the crystallization behaviors and mechanical property of HA/PLGA composite

The crystallization behaviors and mechanical properties of pure PLGA and the two HA/PLGA composites containing 3 wt% surface-modified HA with grain sizes of less than 0.65 μm and 2 μm were investigated by differential scanning calorimeter (DSC), a polarized optical microscopy (POM) and electromechanical universal tester. The crystallization behaviors, isothermal crystallization kinetics analysis and spherulite growth procession observation showed that the morphology of spherulite had no remarkable difference among the three samples. However, the crystallization rate of the HA/PLGA composite with the larger grain size range HA was the fastest, and the bending and tensile strength results showed its mechanical property was also greatly enhanced comparing with the HA/PLGA composite with the smaller grain size range HA and pure PLGA. The above results suggested that the larger grain size range HA, acting as a more effective heterogeneous nucleating agent in HA/PLGA composite, was more benefit to promote the crystallization of PLGA and result in a higher mechanical property of HA/PLGA composites than the small grain size range HA, which would be of guiding significance to select size range of other inorganic particles to improve the mechanical property of PLA or PLGA-based composites in future.