Surface finish enhancement in fused deposition modeling of PLA using chloroform: a comprehensive characterization study

Fused Deposition Modelling is an additive manufacturing method that is gaining popularity to create complex parts. However, the printed product often suffers from poor surface finish. Although various chemical treatment methods have been proposed to enhance the surface finish quality of printed parts, the treatment mechanism and its effect on the mechanical properties of the parts have not been well identified and characterized. The focus of this study is to investigate the impact of chloroform solution concentrations and immersion times on the surface roughness, tensile strength, and impact strength of polylactic acid-printed parts after chemical dipping treatment. Additionally, it seeks to understand and characterise the mechanism through which chloroform affects surface properties and alters mechanical characteristics. For this purpose, a central composite design was used to design a set of 13 experiments with varying levels of concentration and immersion time. The mechanisms underlying the changes in surface roughness, tensile strength, and impact strength were evaluated using scanning electron microscopy and energy dispersive X-ray analyses to evaluate the topography and elemental composition of the treated surface. Thermogravimetric analysis and differential scanning calorimetry were employed to investigate the change in thermal properties and crystallinity. The results reveal a significant reduction in surface roughness on sloped and flat surfaces. Additionally, the treated specimen demonstrated higher impact strength, while a decrease in tensile strength was observed. In addition, structural and elemental compositional changes were noted to the outer surface layer of the specimens.