Preparation and characterization of complex shaped polytetrafluoroethylene (PTFE) parts based on vat photopolymerization 3D printing

Abstract

The utilization of vat photopolymerization (VPP) technology presents a novel approach for the production of PTFE parts with intricate geometries. Nevertheless, excessive exposure during photocuring and deformation warpage resulting from the debinding and sintering procedures significantly impact the printing precision of these parts. To achieve high quality printing of complex shaped PTFE parts, this research undertook a systematic investigation of the vat photopolymerization 3D printing process and characterized the final parts. Initially, an assessment was conducted on the rheological properties of photocuring slurries featuring different levels of solid loadings, and the Jacob working curves were established for varying solid loadings and dye concentrations to elucidate the impact of slurry components on photocurable properties. Through thermogravimetric analysis, the optimum debinding temperature for printed green bodies was determined, resulting in the production of PTFE parts devoid of any defects or distortions and the effectiveness of the debinding process was verified by Raman spectroscopy. Then conducted a characterization of the density and mechanical properties of 3D printed PTFE parts, revealing a density reached 99.0% of the conventionally machined PTFE parts, as well as tensile and yield strengths of 22.04 MPa and 12.57 MPa, respectively. Finally, PTFE micro-structural surfaces were constructed via vat photopolymerization 3D printing process, resulting in favorable hydrophobic performance. These findings contribute to a comprehensive understanding of the 3D printing process for PTFE material and offer theoretical guidance for the effective production of complex shaped PTFE parts.