Composites of Hydroxyapatite Whiskers/poly(L-lactide-co-glycolide) with High Tensile Plasticity

Hydroxyapatite whiskers (HAW) with a maximum aspect ratio of 20 were employed to improve the toughness of poly(L-lactide-co-glycolide) (PLGA). 3-Aminopropyltriethoxysilane (AMEO) was grafted on the surface of the hydroxyapatite whiskers (g-HAW) to improve its wetting in the PLGA matrix. Composites based on HAW, g-HAW, and PLGA were prepared. The structure and properties of the composites were subsequently investigated by powder X-ray diffraction (XRD), scanning electron microscopy, differential scanning calorimetry, and tensile testing. The g-HAW were distributed homogenously in the PLGA matrix because of improved wetting of g-HAW while the HAW were aggregated. The stronger interfacial bonding also gave rise to improved mechanical properties of the g-HAW/PLGA composites. The HAW/PLGA and g-HAW/PLGA composites failed in a tough manner with intensive plastic deformation. The g-HAW/PLGA composite (5 wt% g-HAW) failed at a maximum elongation of 366%, although the tensile strength dropped slightly. The g-HAW/PLGA composite (1 wt% g-HAW) maintained the initial tensile strength of neat PLGA but failed at an equally high elongation of 347%, whereas PLGA failed at an elongation of 11%.