The Surface Structure of Selective Laser Sintering Printed Thermoplastic Polyurethane Elastomers Parts was Improved by Chemical Polishing Method

For the selective laser sintering (SLS) molding of thermoplastic polyurethane elastomers (TPU) parts with large surface roughness and poor mechanical properties, chemical polishing method can reduce the surface roughness of the material surface, this article investigates the effect of chemical polishing process factors on the tensile properties and surface roughness of the TPU specimens and describes the modification mechanism. The results show that the chemical polishing process factors such as solvent type, polishing solution concentration, polishing temperature, polishing time, drying temperature, and drying pressure have an impact on the modification effect, when the solvent is NMP, the concentration of the polishing solution is 10:2 v/v, the polishing time is 60 s, the polishing temperature is 50 °C, the drying temperature is 50 °C, and the drying pressure is at atmospheric pressure, a desirable effect of chemical polishing of the TPU specimen. Compared with the unpolished TPU specimens, the tensile strength is increased by 41%, the elongation at break is increased by 33%, and the surface roughness is reduced by 66%. After chemical polishing of the TPU surface to form a dense soluble film, the contact angle from the unpolished 130.75° reduces to the polished 52.25°, effectively reducing the surface roughness and improving surface wettability.