The Effect of Limestone Particle Size on Hardness of Polylactic Acid/Hydroxyapatite Composite

Abstract

Limestone is a mineral that mainly contained calcium oxide. Limestone has been used in manufacture industries for decades. Many researchers utilized limestone as a material for hydroxyapatite. Hydroxyapatite is a biocompatible material for human body and it is a potential material to restore the damaging bone. However, the hardness of hydroxyapatite is low. In this research, hydroxyapatite made from limestone and disodium hydrogen phosphate dihydrate were mixed with polylactic acid. The limestone was added as a source of calcium and increased the hardness of the composite. Polylactic acid was added to increase the compatibility between the components. The limestone particles sizes effect was studied using limestone powder size of 56 μm, 100 μm, and 150 μm. The composite was prepared by weighting, pre-heating, mixing, heating and pressing of the ingredients. The mechanical characterization was carried out through Micro Vickers Hardness Test. The composition of the composite was analyzed using X-ray Fluorescence. The surface morphology, interface adhesion, and element distribution were observed using scanning electron microscope and energy dispersive spectroscopy. The calcium-phosphor ratio of the composite similar with the one in the human bone. The composite that contained the finer size of limestone powder has the highest hardness. The ratio of the calcium to phosphor is 1.63.