Effect of phytate doped cobalt and copper ion modified carbon nanotubes on flame retardancy and ceramic properties of silicone rubber

Silicone rubber (SR) has excellent properties, such as high and low temperature resistance and weather resistance. However, the flame retardancy of SR is rather poor, which severely limits the range of application of SR. Therefore, it is necessary to make certain modifications in order to improve its flame retardancy. In this study, wollastonite, low-melting glass powder, and phytate-modified carbon nanotubes (CPCC) were added to SR to prepare ceramizable silicone rubber (CSR) composites with good fire safety performance. The effect of CPCC on the flame retardancy and ceramization properties of CSR materials was investigated. The results showed that, with the addition of 3 phr of CPCC, the limiting oxygen index of the CSR composite material reached 33.8%, which was 26.1% higher than that of pure SR, and its UL-94 grade reached V-0 grade. The results of the cone calorimeter test showed that the total heat release of the CSR composite with three parts CPCC was reduced by 26.6%, and the peak heat release rate reduced by 13.1%. In addition, after the CSR6 composite was calcined at 1000°C for 1 h, the ceramic body formed by the composite had good supporting properties, and its bending strength was as high as 6.17 MPa.