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Polylactic acid (PLA) is derived from natural aliphatic polyester resources for instance sugarcane or starch based plants. PLA also known as a biocompatible and biodegradable thermoplastic and found widely in multiple applications like electronic and electrical devices, biomedical, food packaging and the engineering field. PLA have attracted attention in production potential due to its superior attributes like ease of processing, high strength and high modulus. Infill density, raster angle and infill pattern can influence the mechanical characteristics of materials like PLA, acrylonitrile-butadiene-styrene (ABS), polyetheretherketone (PEEK). In this paper, the relationship between infill density and raster angle was studied to investigate the mechanical performances of PLA by using 3D printers. 3D printing is used to fabricate more complex 3D design objects. The tensile test was involved to evaluate the properties of pure PLA. For pure PLA, 0° raster angles with 100% infill density show the highest tensile strength and Young’s modulus which are 28.926MPa and 1262.7MPa respectively. However, a decreasing trend of break elongation reveals in PLA as infill density increases for both 0° and 90° raster angle. Optimization of printing parameters become crucial to provide high quality materials for 3D printing in order for education, packaging, engineering and biomedical applications.

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3D printed polylactic acid (PLA) composites reinforced with zinc oxide (ZnO) were successfully fabricated by attaching a ZnO dispenser beside a MendelMax RepRap Printer. Mechanical and electrical testings were performed to characterize the properties of PLA/ZnO and cPLA/ZnO composites. PLA polymer filament is a biodegradable material with the same strength and modulus as other plastic materials. This work emphasizes the effects of printing parameters (infill density and raster angle) on the mechanical properties and electrical conductivity of PLA/ZnO composites. The combination of 100% infill density and 0° raster angle resulted in a substantial increase in the tensile strength and Young’s modulus, but reduction in break elongation. As the infill density increased and shifted from 90° to 0° raster angle, the storage modulus was enhanced but the damping factor declined. Scanning electron microscope images proved ZnO was dispersed in the PLA matrix. Optical measurements showed a large air gap across the 35% compared to the 100% infill density. Conductive PLA composites (cPLA/ZnO) enhanced electrical conductivity when increasing infill density compared to PLA composites. Therefore, optimizing printing parameters could help manufacturers provide superior quality structure and cPLA composites for electrical and electronic applications due to good electrical conductivity.