Properties of Polyamide-6 Composites Reinforced with Hydroxyapatite Nanospheres

Hydroxyapatite nanospheres (nHA) were first synthesized from (NH₄)₂HPO₄ and CaCl₂ precursors in the presence of poly(vinyl alcohol) templates. The structure and morphology of as-synthesized products were examined by materials characterization techniques. X-ray diffraction patterns and Fourier transform infrared spectra showed that the nHA (50–70 nm) exhibit the crystalline structure and vibration bands of HA. The Ca/P molar ratio of nHA approached the stoichiometric value of 1.67. The nHA were then melt blended with polyamide-6 (PA6), followed by injection molding. Tensile and flexural measurements showed that the tensile and bending strengths of injection molded PA6–10 wt% nHA composite were close to those of human cortical bone. A simulated body fluid immersion test revealed that apatite crystals can be readily deposited on the PA6–10 wt% nHA composite surface after immersion for 30 days.