Effect of benzotriazole‐protected platinum catalyst on flame retardancy and ceramic‐forming property of ceramifiable silicone rubber

The high‐performance ceramifiable silicone rubber was prepared by adding Karstedt's Catalyst which was protected by a complexing agent of benzotriazole, Pt/BTA, to the system of silicone rubber (SR)/aluminum hydroxide (ATH)/ZrSiO 4 /glass dust. In this work, effect of Pt/BTA on flame retardancy and ceramic‐forming property of ceramifiable silicone rubber and its mechanisms were investigated. When Pt/BTA content was 1137.75 ppm, Pt/BTA/SR/ATH/ZrSiO 4 passed UL‐94V‐0 rating and SR/ATH/ZrSiO 4 cannot be rated in the vertical burning test. The total heat release and total smoke production were significantly reduced when Pt/BTA was added. Pt/BTA/SR/ATH/ZrSiO 4 composite can support its own weight when heat‐treated at 600°C, 800°C, and 1000°C and three‐point flexural strength of ceramics increased to 29.47 MPa, which was 102.68% higher than that of SR/ATH/ZrSiO 4 When Pt/BTA content was 1137.75 ppm. The flame‐retardant mechanism is discussed via Thermogravimeter‐Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy spectra. A three‐dimensional network in residues is formed and dramatic depolymerization of polymer backbone can be controlled when Pt/BTA is added in composites. With the addition of Pt/BTA, increased carbon content and formed SiC and CC in residues enhence the quality of char layer, isolating heat and oxygen much more efficiently.