Fabrication of CoFe-layered double hydroxide for flame retardant and smoke suppression of silicone rubber foam

In order to improve the flame retardancy and smoke suppression of silicone rubber foam (SRF), the CoFe-LDH was fabricated by coprecipitation method and used as flame-retardant ingredient in SRF. The influence of CoFe-LDH on the flame retardancy, combustion behavior, and thermal stability of SRF was investigated. The results demonstrate that SRF containing only 1.0 phr CoFe-LDH can pass V-0 rating in the vertical combustion test, with a limiting oxygen index of 28.6%. The total heat release and total smoke production are 22.2% and 61.1% lower than that of SRF, respectively. Moreover, CoFe-LDH can improve the thermal stability of SRF in the high temperature range, and the char residue at 900°C of SRF/LDH composite is obviously higher than that of pure SRF. In addition, to further understand the flame-retardant mechanism of CoFe-LDH, the micromorphology of the char residue and the gaseous products during heating for SRF and SRF/LDH composite were analyzed. The results indicate that CoFe-LDH exhibits excellent flame-retardant effects in both condensed and gaseous phases for its functions of catalysis, carbonization, and nonflammable gas release. This study provides a more efficient and convenient strategy for the flame retardant and smoke suppression research of SRF.