Synergistic effect of diatomite and intumescent flame retardant on flame retardant properties of silicone rubber composites

An inexpensive intumescent flame retardant agent, melamine (MEL), was combined with diatomite (DM) and they were applied in preparation of flame retardant room-temperature-vulcanised silicone rubber (RTV) composites. The flame retardance, thermal stability, tensile performance and morphology of the composites were studied. The combination of DM and melamine (MEL) can significantly improve the flame-retardant and physico-mechanical properties of the RTV composites. Vertical burning test revealed that the RTV/DM/MEL composites exhibited self-extinguishment and better flame retardant properties. Cone calorimeter test showed that the PHRR value of RTV/DM-10/MEL-20 composite was 291 kW/m2, which decreased at least 37.4% compared to pure RTV, 465 kW/m2. In addition, this composite presented a high LOI value of 28.5%. The tensile strength and elongation at break of RTV/DM-10/MEL-5 was 0.18 MPa and 121.6%, which were improved about 63.6% and 93.6% compared with that of pure RTV, 0.11 MPa and 62.8%. The improvement of above properties was attributed to the excellent synergistic mechanism between DM and MEL. This study provided a development insight of polymer composites for flame retardant applications in the rubber industry.