Surface modification of nanohydroxyapatite and its loading effect on polylactic acid properties for load bearing implants

Blends of polylactic acid (PLA) and nanohydroxyapatite (NHA) were prepared through melt-mixing by varying the composition of NHA from 1 to 5 wt%. The tensile properties of the PLA-1 wt% NHA nanocomposite exhibited higher values than neat PLA. Beyond 1 wt% NHA, a drop in tensile properties of the PLA-NHA nanocomposites was observed due to agglomeration and poor interfacial adhesion between NHA and PLA. Therefore, NHA was surface modified (mNHA) using three different surface modifiers namely, 3-aminopropyl triethoxysilane (APTES), sodium n-dodecyl sulfate (SDS) and polyethylenimine (PEI). The surface treatment of NHA was studied through Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray (EDX). Results revealed that the tensile properties increased in order of PLA-5 wt% mNHA (APTES) followed by PLA-5 wt% mNHA (SDS), whereas PEI modified NHA resulted in lower tensile properties. Further, increasing mNHA loading to 30 wt%, decreased the tensile strength due to agglomeration of mNHA. POLYM. COMPOS., 39:2880-2888, 2018. (c) 2016 Society of Plastics Engineers