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

ABSTRACT 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.