摘要
The tracking resistance of silicone rubber was commonly improved by incorporating a large amount (>40 wt%) of inorganic fillers, such as aluminum hydroxide, which severely deteriorated its processability and mechanical properties. In this work, platinum-anchored TiO 2 (Pt@TiO 2 -450) was prepared by impregnating TiO 2 in H 2 PtCl 6 aqueous solution and heating at 450 ℃. It was found that the platinum-anchored rutile TiO 2 (Pt@TiO 2 -R450) and fluorophlogopite nanosheet (FPN) could synergistically promote the ceramization of silicone rubber to significantly enhance its tracking resistance. When the content of Pt@TiO 2 -R450 and FPN was 1.0 phr and 0.5 phr, respectively, the tracking resistance of SR/Pt@TiO 2 -R450 reached 1A4.5 level and the erosion ratio was 0.7%. After heating at 1000 ℃ for 1 h, the organic–inorganic conversion ratio and flexural strength were 47.1% and 7.02 MPa, respectively. High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) spectroscopy revealed that the exposed crystal plane of rutile TiO 2 in Pt@TiO 2 -R450 was (110) plane and oxygen vacancies were generated during high-temperature treatment. The oxygen vacancies could anchor Pt and suppress its aggregation at elevated temperature. Meanwhile, the electron transfer from TiO 2 to Pt reduced the oxidation state of Pt species to enhance the catalytic activity for crosslinking of silicone rubber at elevated temperature, which promoted the organic–inorganic conversion to form ceramic barrier. The skeletal support and barrier effect of FPN further improved the compactness of the ceramic barrier. As a result, the silicone rubber rapidly formed a compact SiOC-like ceramic barrier on its surface when subjected to arc discharge, which efficiently defended arc bombardment and heat transfer. Therefore, the tracking resistance of silicone rubber was significantly enhanced.
危险品化学品经营许可证（带存储）