Flame retardancy and smoke suppression of silicone foams with modified Diatomite and Zinc Borate

To improve the flame retardant performance of silicone foams (SiFs), this paper used modified Diatomate (Dia) and zinc borate (ZB) to prepare flame-retardant SiFs. The experiment applied to study the particle size distribution and surface element content changes before and after modification. Then, the influence of modified Dia and ZB on mechanical, flame retardant and smoke suppression properties were investigated by stretch test, limiting oxygen index (LOI) test, UL-94 test, cone calorimeter test, and smoke density analysis test. The mechanical properties showed that the tensile strength and elongation at break of SiFs with 3.75% modified Dia and 1.25% ZB were improved significantly. In addition, the LOI of SiFs with 3.75% modified Dia and 1.25% ZB was 33.6%, which passed UL-94-V-0. The peak heat release rate (PHRR) and total heat release (THR) were 48.3% and 52.2% lower than that of pure SiFs, respectively. At the same time, SiFs with modified Dia had a better smoke suppression effect. Particularly, the total smoke production (TSP) and smoke production rates (SPR) of SiFs with 3.75% modified Dia and 1.25% ZB were reduced by 98.2% and 84.6% compared with pure SiFs.