Effect of hydroxyapatite with different morphology on the crystallization behavior, mechanical property and in vitro degradation of hydroxyapatite/poly(lactic-co-glycolic) composite

This work describes the effect of hydroxyapatite with different morphology of nano-particle (n-HA) and whisker (w-HA) on the properties of hydroxyapatite/poly-lactic-co-glycolic acid (HA/PLGA) composite. The crystallization behavior, mechanical property and in vitro degradation of HA/PLGA composite were studied by scanning electron microscope, differential scanning calorimeter, polarized optical microscopy, electromechanical universal tester and soaking in simulated body fluid (SBF) at 37 °C for 2, 4, 8, 12 and 16 weeks, comparing with pure PLGA. The results showed that n-HA had better mechanical increment effect for PLGA than w-HA, because of the more uniformly dispersion in PLGA matrix without any cavities and the better promotion crystallization effectiveness in HA/PLGA composite than w-HA. However, the in vitro degradation showed that w-HA could keep denser microstructure so that the w-HA/PLGA composite had lower bending strength reduction percent than the n-HA/PLGA composite, owing to the higher crystallinity of w-HA and the more perfectly microcrystalline of PLGA (PLGA/w-HA) than n-HA. The study would be of guidance to select the suitable filler for poly(lactic acid) (PLA) or PLGA polymers in manufacturing bone fracture internal fixation material in future.