Biomimetic synthesis and mechanical properties of hydroxyapatite/poly (vinyl alcohol) nanocomposites

Hydroxyapatite/poly(vinyl alcohol) (HAp/PVA) nanocomposite samples were prepared by two different methods of direct mixing and an in situ biomimetic HAp crystallisation in the presence of polymer. Polymer weight fraction was the variant in both procedures. The prepared samples were characterised with regard to their mechanical properties by performing tensile tests on hot pressed samples. The phase composition and microstructural studies were conducted using X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. Fourier transform infrared (FTIR) was used to determine possible interaction between polymer and HAp during mineralisation processes. The results suggest that a molecular interaction is operative between the side groups of the polymer and the growing HAp crystallites in the in situ process. The enhanced interfacial interaction between the polymer and the reinforcement material led to improved mechanical properties (i.e. higher tensile strength and strain at failure values) for the composite samples prepared by the in situ procedure. An increase in the young's modulus values with increasing filler content was observed for the composite samples prepared by both processes. However, the increase was less in the samples prepared by the in situ process indicating higher strain at a particular stress level.