Evaluation of Anisotropic Deformation and Fracture Properties in Extruded HAp/PLLA Composites

A novel bone regeneration technology is expected to be developed using scaffolds and activities of osteoblasts, instead of the traditional bone filling surgery. Here, the cellular bone formation activities are accelerated by the transplantation of porous scaffold materials as bone filling substitutes, resulting the complete bone regeneration by hydrolytic resorption of scaffold materials and replacement to newly formed bone [1]. The biocompatible composite materials composed of hydroxyapatite (HAp) particles and poly-L-lactic acid (PLLA) are strong candidates for scaffold materials, owing to their bone-conductivity and biodegradability [2]. However, the poor fracture properties [3] are one of the factors limiting their practical application. In order to improve their fracture toughness, the uniaxiallyextruded HAp/PLLA composites had been recently developed via the hydrostatic pressure extrusion molding [4]. In order to establish the microstructural designing principle, it is necessary to understand the relation between the deformation/fracture properties and the microstructure anisotropy. In the present study, the static tensile tests were carried out for uniaxially-extruded neat PLLA and HAp/PLLA composites, in order to evaluate the basic deformation and fracture properties. The anisotropy in the deformation and fracture properties was discussed from the viewpoint of the microstructure observation.