Thermal expansivity and degradation properties of PLA/HA and PLA/βTCP in vitro conditioned composites

Abstract

The objective of this study was to investigate the thermal expansivities and degradation properties for several in vitro conditioned biodegradable poly(lactic acid)/hydroxyapatite (PLA/HA) and poly(lactic acid)/β-tricalcium phosphate (PLA/βTCP) composites with different mass% of the particle reinforcements (i.e. 10, 20 and 30). The samples were prepared by extrusion followed by injection moulding and incubated in a customized simulated body fluid at 37 °C over 60, 90, 120, 150 and 180 days, respectively. Thermal expansion and degradation properties of in vitro conditioned samples, along with dynamic mechanical properties of unconditioned ones, were systematically investigated through coefficients of linear thermal expansion and thermal strain changes, decomposition temperatures, mass changes and per cent residues. The results indicated that PLA/βTCP composites performed better than PLA/HA composites, irrespective of their filler mass%, revealing high values of glass transition temperatures, around a mean value of 65 °C, both on dynamic mechanical analysis and on dilatation measurements but lower values on their degradation temperatures, such as 360 °C. The results suggest the feasibility of tailoring high-loaded osteoconductive fillers-reinforced PLA composites for various medical and engineering applications.