High‐impact polystyrene (HIPS) flame retarded by magnesium hydroxide (MH) was treated in water at different conditions. The effect of water erosion on flame retardancy of the HIPS/MH composite and its mode of action was investigated by various means. The results indicate that both limiting oxygen index value and UL‐94 rating of the HIPS/MH composite decrease observably after water erosion. The average heat release rate, average mass loss rate, total heat release, and total smoke release of the composite all increase remarkably after water erosion. The MH content in the surface layer of the HIPS/MH composite reduces, and the surface of this composite becomes rough and porous after erosion. The water‐eroded composite shows a loose and discrete surface morphology after subjected to fire, which favors heat transfer and mass exchange between flame area and the underlying polymers. Consequently, both flame retardancy and smoke suppression of the polymer composite decrease significantly. The decrease in flame retardancy occurs in condensed phase. The result of this work has provided a basis for further investigations to prevent this detrimental effect induced by water erosion.

中文翻译：

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水蚀对高抗冲聚苯乙烯/氢氧化镁复合材料阻燃性的影响及其作用方式

氢氧化镁（MH）阻燃的高抗冲聚苯乙烯（HIPS）在不同条件下的水中进行了处理。通过各种方法研究了水蚀对HIPS / MH复合材料阻燃性的影响及其作用方式。结果表明，水蚀后，HIPS / MH复合材料的极限氧指数值和UL-94等级均明显降低。在水蚀之后，复合材料的平均放热率，平均质量损失率，总放热和总烟雾释放均显着增加。HIPS / MH复合材料表面层中的MH含量降低，腐蚀后该复合材料的表面变得粗糙且多孔。经过水侵蚀的复合材料在遭受火烧后表现出松散且离散的表面形态，这有利于火焰区域和下面的聚合物之间的传热和质量交换。因此，聚合物复合材料的阻燃性和抑烟性均显着降低。阻燃性的降低发生在冷凝相中。这项工作的结果为进一步研究防止水蚀引起的有害影响提供了基础。