Polyborosilazane-Modified Silicone Rubber Composites With Ceramifiable Self-Supporting Property and Their Ablation Resistance

High-performance anti-ablation silicone rubber materials play a crucial role in the thermal protection systems of electric vehicle battery packs. However, conventional flame-retardant silicone rubbers containing fillers often suffer from poor ablation resistance at high temperatures and inadequate structural integrity. In this work, a novel approach was proposed in which the liquid ceramic precursor polyborosilazane (PBSZ) was incorporated into methyl vinyl silicone rubber via melt blending to construct a ceramic-forming network, thereby preparing ceramifiable, flame-retardant composite materials. Compared with unmodified silicone rubber, the composite containing 6 wt% PBSZ exhibited a 78°C increase in initial decomposition temperature, achieved a limiting oxygen index (LOI) of 25.6%, and reached a flexural strength of 12.68 MPa after treatment at 1000°C. Furthermore, after exposure to a 1000°C flame for 1 min, the back-surface temperature remained below 300°C. As the temperature increases, the flexible silicone rubber undergoes ceramization, forming a dense and stable ceramic structure. This work provides a promising strategy for the development of high-performance, flexible, and ablation-resistant materials.