3D printing biopolymer: A comprehensively experimental study of interfacial bonding performance

Abstract

Additive manufacturing (AM) technologies have experienced a substantial growth in recent decades. AM technologies are able to fabricate and build complicated customised geometry composites without extra tools and execute multi-materials manufacturing that conventional manufacturing methods cannot offer. Polymeric material applied in AM has become the mainstream, but industrialisation still faces many challenges. Currently, bio-based polymers have also been highly demanded due to the sustainability requirements. The combination of AM and bio-based polymeric material shows significant potential in a wide range of applications. This study has presented a comprehensive investigation programme focusing on the interface formulation, structure, bonding and performance of 3D printed biopolymeric materials. The experimental analysis firstly investigated the interfacial bonding performance of various bio-based polymeric materials in detail, then several material combinations and modifications have been investigated in order to enhance the printability and performance of AM biopolymeric materials. The formation mechanisms, failure modes and micromechanical performance of interlaminar bonding were comprehensively studied throughout the work programme. The printing performance was determined by the density profile, mechanical properties testing and micromechanical properties across the thickness and over cross-section area for all the materials studied. Thermal properties have also been carried out in order to determine the miscibility of the copolymers. The optimised printing parameters and the effect of postprocess of Polylactide (PLA) polymer have been generated following this programme, up to 24% higher in tensile strength when the printing temperature is 220 ˚C compared to the 200 ˚C. Impressive mechanical strength obtained but severe anisotropy property and brittleness have also existed. The reduction of tensile strain in y-axis specimens compared to the x-axis has improved from 62% to 22% and competitive mechanical properties have also been achieved by the addition of PHBV biopolymer into the PLA, up to 86% increase in tensile strain has been achieved. Lastly, innovatively bio-based printing materials, such as Polylactide (PLA)/Polybutylene Succinate (PBS) and Polylactide (PLA)/Polybutylene Succinate (PBS)/Polyethylene glycol (PEG), have been investigated and up to 80% increase in ductility has been achieved in PLA/PBS/PEG blends. While the limited improvement has been achieved in the PHBV modifications and some challenges emerged and remained for further development, such as the anisotropy, brittleness, processability and geometric accuracy, a promising path is provided by this study to extend further research and commercial applications of bio-based polymers for additive manufacturing.