Study on combustion properties of magnesium oxysulfate cement/polystyrene composites

In order to solve problem that polystyrene is inflammable and easy to produce poisonous gasꎬ magnesium oxysulfate cement and polystyrene particles were used to make magnesium oxysulfate cement / polystyrene composite material. Thenꎬ effects of different ratios of lightly ̄burned magnesium oxide and heptahydrate magnesium oxysulfate on combustion performance of polystyrene particles were studied by LOI testꎬ UL-94 vertical combustion testꎬ smoke density testꎬ and TGA. The results show that when content of magnesium sulfate maintains unchangedꎬ weightlessness range and rate of polystyrene composites decreases with the increase of lightly ̄burned magnesium oxideꎬ and so does the maximum mass loss rate while residual carbon rate increases with it at 700 °C with its maximum rate able to reach 80􀆰 73%. LOI of polystyrene coated with magnesium oxysulfate cement can reach up to 37􀆰 2%ꎬ and it increases along with 中 国 安 全 科 学 学 报 China Safety Science Journal 第30卷 2020年 that of magnesium oxysulfate when lightly ̄burned magnesium oxide stays fixed. It shows the same trend of LOI increasing along lightly ̄burned magnesium oxide when the other is unchanged. UL 94 level of composite materials can all reach V-0ꎬ and their smoke density is about 30 times lower than that of pure polystyrene particles. Flame retardation and smoke suppression of polystyrene are significantly improved by magnesium oxysulfate cement.