可陶瓷化PE/EVA/MH/PCS复合材料阻燃性能与绝缘性能研究

Study on Flame Retardancy and Insulation Properties of Ceramizable PE/EVA/MH/PCS Composites

低烟无卤阻燃聚烯烃材料已成为保护人类生命及财产安全、保障生产生活正常进行的重要材料而得到广泛的应用,但因无机阻燃剂阻燃效率低而需要高添加量,使其阻燃材料综合性能降低,影响在高端领域的应用。该文采用聚碳硅烷协同氢氧化镁阻燃改性聚乙烯/乙烯–醋酸乙烯酯共聚物复合材料,研究聚碳硅烷(polycarbosilane,PCS)与氢氧化镁(magnesium hydroxide,MH)之间的协同作用及阻燃剂微观相分布对复合材料阻燃性能、燃烧行为及电性能的影响。实验结果表明,当阻燃剂总添加量为40%时,复合材料的极限氧指数达到28.3,热释放速率峰值降低了38%,总热释放降低39%,燃烧性能得到改善;PCS不影响复合材料的热降解行为,在燃烧过程中形成无定形相将氢氧化镁分解生成的MgO颗粒粘结在一起形成致密的陶瓷化炭层;两步混制备方法影响MH的分布,有利于提高复合材料电性能,体积电阻率提升26%,电击穿性能提升22%。研究结果可为低烟无卤阻燃聚烯烃材料的开发及在高端领域应用提供理论支撑及实践基础。

Low smoke halogen-free flame retardant polyolefin materials have been an important material in protecting the safety of human lives and property as well as ensuring the normal production and living. However, the low flame retardant efficiency of inorganic flame retardants leads to high loading, which decreases the comprehensive performance of the materials and affect the application in high-end fields.Here, polyethylene(PE)/ethylene-vinyl acetate copolymer(EVA) composites are modified by polycarbosilane(PCS) and magnesium hydroxide(MH). The synergistic effect between PCS and MH and the effect of flame retardants distribution on flame retardancy, combustion behavior and electrical properties of composites are studied. The results show that, the combustion performance is improved with total amount of flame retardant 40%;the limiting oxygen index(LOI) of the composite reaches to 28.3;the peak heat release rate decreases by 38%;the total heat release decreases by 39%.Polycarbosilane does not affect the thermal degradation behaviors of the composites;the amorphous phase formed in the combustion process bonds the magnesium oxide particles together, forming a dense ceramic char. The two-step blending preparation method affects the distribution of MH, which is beneficial to improve the electrical properties of the composites. The volume resistivity increases by 26%, and the electrical breakdown strength increases by 22%. The research provides theoretical support and practical basis for the development and application of low smoke halogen-free flame retardant polyolefin materials in high-end fields.