Effect of sepiolite on properties of silicone rubber/melamine/starch/sepiolite flame retardant composites

In this work, a novel silicone rubber composite with low smoke, good mechanical property, and excellent flame retardant was prepared by introducing melamine (MEL), starch (St), and sepiolite (SEP) into SR. The effect of the amount of SEP on the mechanical properties of SR composites was investigated. The results showed that the mechanical properties were optimal when the amount of SEP was 30 phr. The tensile sections of the composites were characterized by SEM. The flame retardant properties of the composites were evaluated by oxygen index, vertical combustion, and cone calorimetry test (CCT). The thermal stability of the composites was tested by TGA. The flame retardant mechanism of the composites was also discussed. It was found that the strength and stability of the carbon layer of the composite were remarkably enhanced, and the flame retardant properties of the materials were improved with the addition of SEP. The SEM images of CCT carbon residues revealed that the carbon layer of the composite with SEP was more stable and had fewer cracks than that without SEP. This work provides new insights for the preparation of high-performance SR composite.