Additive manufacturing of PTFE TPMS structures with excellent mechanical properties under extreme high and low-temperature

Polytetrafluoroethylene (PTFE) has become an important engineering polymer due to its unparalleled chemical inertness and wide operating temperature range. In this study, complex, intricate, and high-performance PTFE components were prepared using Vat Photopolymerization (VPP) technology, and their composition design and microstructural evolution were investigated. Additionally, the effects of heat treatment processes and cooling rates on mechanical properties were further analyzed. When the sintering temperature was 410 °C, the holding time was 90 min, and the cooling rate was 3 °C/min, the density of PTFE reached 99.8 % of traditionally processed PTFE parts, while achieving excellent mechanical properties, with a tensile strength of 25.3 ± 0.2 MPa and an elongation at break of 224± 5 %. Furthermore, the tensile strengths at −150 °C and + 150 °C were 49.2 ± 4.3 MPa and 5.9 ± 3.0 MPa. Subsequently, the mechanical properties of TPMS with different structures and porosities were investigated under high and low temperatures. At room temperature, the compressive strength at 10 % deformation ranged from 1.2 to 4.3 MPa for different minimum surface areas. Under low-temperature conditions (−150 °C, −80 °C), the stiffness and strength of the PTFE structure significantly increased, with compressive strength at 10 % strain ranging from 5.3 to 15.4MPa, indicating a shift in the failure mechanism due to increased material brittleness. Conversely, high temperatures (+200 °C, +150 °C) cause PTFE to soften significantly, with compressive strength ranging from 0.4 to 1.1MPa at 10 % strain, and a substantial decrease in stiffness and strength, reflecting highly plastic deformation behavior.