Mechanical and tribological performance of molded and 3D-printed polymers under environmental degradation

This study evaluates the mechanical and tribological performance of Acrylonitrile Butadiene Styrene (ABS) and Polyethylene Terephthalate Glycol (PETG) produced by fused deposition modeling (FDM) and molding under accelerated ultraviolet (UV) and moisture exposure. Specimens were exposed for 300, 600, and 900 h, and changes in microstructure, flexural behavior, surface roughness, hardness, and abrasion resistance were quantified. 3D-printed ABS exhibited the greatest degradation after only 300 h of exposure, with flexural ductility decreasing by more than 27%. A reduction in plowed area of approximately 41% in abrasion testing was consistent with the loss of ductility in the 3D-printed ABS samples. These samples showed poor abrasion resistance, with a debris-to-indentation ratio of about 89% throughout the exposure period. Molded ABS showed minimal degradation in flexural properties; however, it also exhibited poor abrasion resistance, with a debris-to-indentation ratio exceeding 76% after 300 h of exposure. PETG specimens demonstrated higher environmental stability and abrasion resistance in both the 3D-printed and molded forms. Molded PETG maintained the lowest material removal during abrasion, with a debris-to-indentation ratio below 20% throughout the exposure, indicating the highest abrasion resistance. Its hardness increased significantly, by approximately 20% after 300 h of exposure, reflecting UV-induced embrittlement. Molded PETG also exhibited surface microcrack formation after environmental exposure, accompanied by increases in the roughness parameters Ra and Rz and a decrease in surface skewness (Rsk), a shift consistent with the development of microcracks and deeper surface grooves. These results highlight the strong influence of manufacturing method on polymer durability under environmental degradation.