Fire reaction properties of polystyrene-based composites using hollow silica as synergistic agent

Hollow silica microsphere (h-SiO2) has been widely applied in the field of thermal insulation, catalyst supports and drug storage/delivery containers. In this research, h-SiO(2)has been innovatively used as synergistic agent to enhance the flame retardancy of intumescent flame-retardant polystyrene. The synergistic effects of h-SiO(2)on intumescent flame-retardant polystyrene have been studied by limiting oxygen index (LOI), UL-94 test and cone calorimeter test (CCT). When 0.5 mass% h-SiO(2)was substituted for the intumescent flame-retardant additive, the LOI of polystyrene composite (PS/IFR/Si0.5) increased by 5 units and the composite preserved the V-0 rating. Manipulation of parameters from CCT indicated that the peak heat release rate was reduced by 27% for the PS/IFR/Si0.5 composite, whereas the total heat release decreased by 14.5% and the ratio of residue increased by 85.6% (from 13.2 to 24.5%) compared to those of the composite without h-SiO2. The synergistic effects of h-SiO(2)on intumescent flame-retardant polystyrene are attributed to physical and chemical processes in the condensed phase. The morphologies of charred layer after CCT proved that h-SiO(2)induced compact charred layer with enhanced thermal and gas barrier effect, which in turn protected the inner matrix from combustion and decreased specific extinction area by 24.2%.

Automated summary

Hollow silica microsphere (h-SiO2) has been used as a synergistic agent to enhance the flame retardancy of intumescent flame-retardant polystyrene. The incorporation of h-SiO2 resulted in improved limiting oxygen index (LOI), reduced peak heat release rate, increased residual ratio, and a more compact charred layer with enhanced thermal and gas barrier effects.