Enhancement of Flame Retardancy and Mechanical Properties of Compression‐Molded Silicone Rubber Foam With Core–Shell SiO 2 @ LDH Particles

ABSTRACT High‐temperature vulcanized silicone rubber (HTV‐SR) foams with high loadings of flame retardants typically exhibit poor processability and compromised thermal insulation performance when prepared by compression molding. In this study, a novel flame‐retardant system composed of hydrophobic core–shell SiO 2 @LDH particles and a platinum–amine coordination compound was developed for HTV‐SR foams. The core–shell SiO 2 @LDH particles exhibit ultrathin LDH nanosheets and a high specific surface area of 224.3 m 2 g −1 , enabling good dispersion in the HTV‐SR matrix. Silicone rubber compounds containing a unique core–shell nanostructure of SiO 2 @LDH show excellent processability, allowing for easy preparation of HTV‐SR foam with a high expansion ratio by standard compression molding. SiO 2 @LDH exert a pronounced flame‐retardant effect for HTV‐SR foam in both the gas and condensed phases. A synergistic effect is achieved by employing a small amount of platinum–amine coordination compound, which promotes a robust char layer at high temperatures and enhances flame inhibition of the SR/SiO 2 @LDH foam. With only 15 phr of SiO 2 @LDH particles, the SR/SiO 2 @LDH foam achieves a UL‐94 V‐0 rating and a limiting oxygen index (LOI) of 33.5%. Furthermore, the SR/SiO 2 @LDH foam shows a high expansion ratio with low density (0.35 g/cm 3 ), low thermal conductivity (0.076 W/(m K)), high tensile strength (237.1 kPa), elongation at break (205.8%), and rebound resilience (7.2%). This study presents an advanced flame‐retardant system for HTV‐SR foams compatible with continuous compression molding, producing a flame‐retardant foam with exceptional mechanical and thermal insulation properties.