Effects of particulate morphology on the tensile behaviour of polymer-hydroxyapatite composites

This study examines the effect of powder morphology on the tensile properties of polymer-hydroxyapatite (HA) composites. Experimental findings show that the surface morphology and structural integrity of the HA powder have considerable influence on the tensile property of the composites. The tensile modulus was observed to be dependent on the surface characteristics of the powder. HA powder with rough surfaces was found to promote mechanical interlocking and improved interfacial bonding, hence resulting in higher tensile modulus than powder with smoother surfaces. The tensile strength of the composite was governed predominantly by the composite weaknesses, which were either interfacial or structural in nature. Relatively lower tensile strength was achieved with porous agglomerated HA powder that easily fractured in a brittle manner. Dense spherical HA powder prevented the initiation and propagation of sharp cracks, resulting in higher tensile strength provided good interfacial bonding was assured. Finally, a combination of high strength and modulus was achieved by applying appropriate post-treatment to microwave sensitive materials.