Pre- and post-processing of PET-G 3D prints of honeycomb cellular structure for high energy absorption and surface engineering

Upon an impact, the resulting energy is manifested through unwanted damage to objects or persons. Therefore, it is essential to improve protective materials such that the system reduces injuries to the involved moving parts by the selection of material properties, design, and manufacturing processes. New materials with enhanced energy absorption capabilities are made of cellular structures. The hexagonal honeycomb structure is one of the most well-known for its space-filling capacity, structural stability, and high energy absorption potential. Additive Manufacturing (AM) technologies have been effectively useful in a vast range of applications. The evolution of these technologies has been studied continuously, focusing on improving mechanical and structural characteristics of the 3D printed models, such as fracture toughness to resist impacts and crack propagation to create complex quality parts that not only satisfy design requirements but also functionality, mechanical properties, and cost. An accessible manufacturing technology, for creating complex structures, is Fused Deposition Modeling (FDM). Nevertheless, this method has adverse surface features related to its layer by layer deposition. In this study, the 3D honeycomb structures of polyethylene terephthalate glycol (PET-G) were fabricated by the FDM method. The process parameters considered are infill density and layer printing orientation. The effectiveness of the design is investigated by performing in-plane compression tests. The set of parameters that produces superior results for better energy absorption capabilities is determined by analyzing the welding between filament layers in the printed object by the FDM technology. The structures were subjected to a vaporized solvent bonding post-processing technique, and the investigation highlights the rationale of interlayer diffusion response and adhesion strength by applying a sol-gel hydrophobic coating. This study utilized roughness, hardness, and contact angle analyses to provide a better understanding of the solvent-polymer interactions to gain insight into the advantages and limitations of this technique.