Experimental investigation of 3D printed polylactic acid and polylactic acid – hydroxyapatite composite through material extrusion technique for biomedical application

In biomedical industries, composite additive manufacturing are employed for customization, quicker production, efficient use and capital reduction. This experimental work focuses on the development of poly lactic acid (PLA) and novel extruded hydroxyapatite (HA) reinforced poly lactic acid (HPLA) by material extrusion (ME) technique and their properties were compared with that of standard 3D printed PLA. The extruded composite filaments were subjected to thermal characterization (DSC, TGA) and chemical characterization (FTIR) to ensure filament quality and its implementation in ME technique for 3D printing process. In addition, the melt compounded composite filaments were subjected to annealing to observe the influence of heat treatment upon their mechanical properties and thereby to validate their potential to resist breakage during ME process. Taguchi orthogonal array method using MiniTab software is employed to execute the parameter optimization for the 3D printing process. The 3D printed tensile, flexural and impact specimens, using pure PLA and extruded composite filaments, as per American Society for Testing and Materials (ASTM) standards were subjected to a comparative experimental study which showed that 3D printed specimens using PLA and HPLA performed better than that of standard PLA specimens due to the improvement in their crystalline nature. The ruptured specimens were subjected to microstructural characterization (optical microscopy, SEM) to observe failure modes and ash content test was conducted to validate the homogenous distribution HA filler particles in PLA matrix. In addition, mechanical characterization was also performed on 3D printed bone plate/bone scaffold application using extruded filaments of PLA and HPLA, as per ASTM F543 standards, to validate incorporation of the composite filaments in real-time application in biomedical industry.