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Naturally, bones have a remarkable capacity to regenerate in case of minor injury and continuously remodel throughout an adult life. However, major injuries involving the load bearing bones, such as spine, hips and knee, require orthopaedic surgeries. These bone implants are made from biomaterials. As a result, this study investigates the use of biomaterials such as poly-lactic acid (PLA), nanohydroxyapatite (NHA) and graphene nanoplatelets (GNP) for applications related to bone implants. In this study, NHA was synthesised using precipitation method assisted with ultrasonication. The process parameters (reaction temperature, ultrasonic time and amplitude) were optimised using response surface methodology (RSM) based on 3 factors and 5 level central composite design (CCD). Upon characterisation, the synthesised NHA was confirmed to mimic the HA present in the human bone both chemically and morphologically. The synthesised NHA was then compounded with PLA matrix via melt-mixing by varying the NHA loading (1-5wt%). The impact strength of the PLA-NHA nanocomposites increased with NHA loading, attaining 21.6% enhancement in comparison to neat PLA. In contrast, the tensile strength and modulus of the PLA-NHA nanocomposites exhibited an initial increase of 0.7% and 10.6%, respectively, for 1wt% NHA loading, but deteriorated with the increasing NHA loading. The FESEM microstructures of the impact fractured samples also depicted agglomeration of NHA particles and poor interfacial adhesion between NHA and PLA. Hence, to improve the dispersion, NHA was surface modified (mNHA) using three different surface modifiers namely, 3-aminopropyl triethoxysilane (APTES), sodium n-dodecyl sulfate (SDS) and poly-ethylenimine (PEI). The FESEM analysis revealed an improved interfacial adhesion between PLA matrix and mNHA(APTES), which, enhanced the mechanical, thermal and dynamic mechanical properties of the PLA-5wt%mNHA(APTES). Meanwhile, mNHA(SDS) and mNHA (PEI) had no significant effect

Naturally, bones have a remarkable capacity to regenerate in case of minor injury and continuously remodel throughout an adult life. However, major injuries involving the load bearing bones, such as spine, hips and knee, require orthopaedic surgeries. These bone implants are made from biomaterials. As a result, this study investigates the use of biomaterials such as poly-lactic acid (PLA), nanohydroxyapatite (NHA) and graphene nanoplatelets (GNP) for applications related to bone implants. In this study, NHA was synthesised using precipitation method assisted with ultrasonication. The process parameters (reaction temperature, ultrasonic time and amplitude) were optimised using response surface methodology (RSM) based on 3 factors and 5 level central composite design (CCD). Upon characterisation, the synthesised NHA was confirmed to mimic the HA present in the human bone both chemically and morphologically. The synthesised NHA was then compounded with PLA matrix via melt-mixing by varying the NHA loading (1-5wt%). The impact strength of the PLA-NHA nanocomposites increased with NHA loading, attaining 21.6% enhancement in comparison to neat PLA. In contrast, the tensile strength and modulus of the PLA-NHA nanocomposites exhibited an initial increase of 0.7% and 10.6%, respectively, for 1wt% NHA loading, but deteriorated with the increasing NHA loading. The FESEM microstructures of the impact fractured samples also depicted agglomeration of NHA particles and poor interfacial adhesion between NHA and PLA. Hence, to improve the dispersion, NHA was surface modified (mNHA) using three different surface modifiers namely, 3-aminopropyl triethoxysilane (APTES), sodium n-dodecyl sulfate (SDS) and poly-ethylenimine (PEI). The FESEM analysis revealed an improved interfacial adhesion between PLA matrix and mNHA(APTES), which, enhanced the mechanical, thermal and dynamic mechanical properties of the PLA-5wt%mNHA(APTES). Meanwhile, mNHA(SDS) and mNHA (PEI) had no significant effect