Effects of in situ biomineralization on microstructural and mechanical properties of hydroxyapatite/polyethylene composites

To improve the mechanical properties of hydroxyapatite (Ca-10(PO4)(6)(OH)(2); HAP)/High-density polyethylene (HDPE) composites, the process of in situ biomineralization was used, and its effect on the microstructure and mechanical properties of HAP/HDPE composite was investigated by means of Fourier transform infrared spectroscopy, energy dispersive X-ray analysis, scanning electron microscope, Instron testing machine, and Ceast Impact tester at room temperature. Results show that: (1) the HAP/HDPE composite prepared by in situ biomineralization has the better mechanical properties. The impact strength and the tensile strength reach 712 J/m and 96 MPa, respectively, which were more than three times higher than those of composites prepared by blending directly. (2) The biomineralized HAP crystals grew onto the HDPE with chemical bond and dispersed in HDPE polymer on the level of nanometer dimension, which provided a greater surface area for bonding with the polymer, accordingly enhancing the interfacial bonding strength. On the other hand, the higher interfacial bonding strength will produce interfacial stress from the contraction of matrix, which can strain-induce the crystallization of matrix to form the extended-chain crystal structure in the area surrounding the filler. As a result, the mechanical properties of composite improved greatly. (c) 2006 Wiley Periodicals, Inc.