Evaluating the effect of varying infill density and graphene reinforcement on water absorption properties of PETG composites fabricated via fused deposition modeling (FDM)

Purpose This study aims to investigate the influence of varying infill density and graphene reinforcement on the water absorption characteristics of polyethylene terephthalate glycol-modified (PETG) composites fabricated using Fused Deposition Modeling (FDM). Unlike previous studies that focused primarily on mechanical properties or single-variable effects, this research comprehensively analyzes moisture resistance by considering both structural and material aspects. Design/methodology/approach Six PETG-based composites, including neat PETG and PETG reinforced with 0.02 Wt.%, 0.04 Wt.%, 0.06 Wt.%, 0.08 Wt.% and 0.1 Wt.% of graphene, were 3D-printed at three different infill densities (100%, 75% and 50%) via FDM. The composites were immersed in distilled water, saturated salt and saturated sugar solutions to evaluate their water absorption behavior. Findings Results indicate that 100% infill density consistently exhibited the lowest water absorption due to reduced porosity and stronger layer adhesion, whereas 50% infill density showed the highest due to increased voids and weaker bonding. Among the compositions, 0.04 Wt.% graphene demonstrated the best moisture resistance, with the lowest water absorption at 100% infill density (5.235%) in distilled water, while neat PETG at 50% infill density showed the highest water absorption (39.055%) in the saturated salt solution. Regarding solutions, distilled water resulted in the lowest absorption rates, whereas saturated salt solution caused the highest absorption due to ion interactions with PETG. These findings establish that 100% infill density combined with 0.04 Wt.% graphene provides optimal water resistance due to enhanced structural integrity and effective graphene dispersion, making it ideal for moisture-sensitive applications. Originality/value This study offers valuable insights for optimizing PETG/graphene composites for aerospace, marine and humid-environment applications.