Adding Paraffin Wax Improves the Thermal Insulation and Ablative Properties of Liquid Silicone Rubber Composites

ABSTRACT This study relies on the high ablation resistance strategy of char layer expansion ceramization to strengthen the char layer and improve ablation performance. The use of phase change material, that is, paraffin wax, was effective in simultaneously improving the ablation resistance and thermal insulation performance of liquid methyl vinyl silicone rubber (LMVSR) composites, which was attributed to the low density, enhanced char layer, and improved heat‐absorption capacity. The introduction of paraffin wax lowered the ablation temperature and increased the specific heat capacity of LVMSR‐based composites, thereby enhancing heat dissipation and reducing thermal erosion. In addition, paraffin wax was able to promote the ceramization reaction. The mass erosion rate, pyrolysis rate, and graphitization degree of the char layer were significantly improved when the content of paraffin wax was increased from 5 to 15 phr. The composites with 15 phr paraffin wax demonstrated the best performance and the highest modification effect. The paraffin modification was effective in reducing the mass ablation rate, especially at 10 phr, which showed a decrease of 34.43% when compared with that of the L‐P0 counterpart. The maximum back‐face temperature was reduced by 29.63% upon adding 15 phr paraffin wax when compared with L‐P0, exhibiting excellent thermal insulation performance. The above results showed that the ablative resistance, internal erosion resistance, and thermal insulation properties of silicone rubber‐based composites were significantly improved by using the strategy of expansion ceramization and enhanced heat absorption/dissipation by adding phase change materials, which shows potential application in preparing flexible thermal ablative material for thermal protection purposes.