摘要
目前,随着经济的不断发展,我国农村电网改造和城市化建设的发展对电缆的需求量逐年增加,而用于电缆绝缘层和护套层的高分子材料的需求也不断上升。这种需求的上升不仅仅体现在数量上的提高,而且在质量上也要求不断的进步。特别是欧盟的RoHS指令的实施以后,明确规定了将严格地限制六种有害物质在电子电气设备中的使用,因此,一些含有害物质的阻燃电缆料将在不久的将来逐步退出历史舞台,尽管PVC电线电缆还没有完全限制,但是全球无卤化的电线电缆的需求不断增大,而高品质的无卤阻燃环境友好的电缆料的开发将是一个新的课题。
聚烯烃弹性体POE分子链饱和,属于非极性材料,因此具有良好的电气绝缘、耐氧、耐臭氧以及耐高温老化性,这些性能都非常适合应用于电缆的护套材料,因此POE可以作为电缆的包覆材料,取代原来的PVC、氯丁橡胶、氯磺化聚乙烯等包覆材料,有很大的市场需求和应用前景。
本文利用硅烷交联技术改性聚烯烃弹性体POE,采用氢氧化镁作为主要的无卤阻燃剂,EVA作为交联POE和氢氧化镁之间的增容剂,并且采用微胶囊化红磷(MRP)、氰尿酸三聚氰胺(MCA)、磷氮复合阻燃剂(ZR3)以及含硅有机阻燃剂(ASBP)等不同的阻燃协效剂协同阻燃氢氧化镁,并制备出了一种力学性能和阻燃性能优异,加工性能、电学性能和耐高温老化性能优良的无卤阻燃电缆料,满足具有较高安全性要求的场所的应用。首先,探讨了氢氧化镁含量对交联POE的阻燃性能、拉伸性能、热延伸试验、耐高温老化性能以及电学性能的影响。研究表明氢氧化镁含量为140phr时,制备的无卤阻燃交联POE复合材料有着良好的阻燃性能、拉伸性能、耐高温老化性能和电学性能,并且能通过电缆材料的热延伸试验。其次,研究了增容剂EVA含量对交联POE和氢氧化镁之间相容性的影响,试验结果表明当采用10phrEVA作为增容剂时,复合材料阻燃性能没有降低,而耐高温老化性能和断裂伸长率得到有效地提高,并且能通过电缆材料的热延伸试验。最后,采用微胶囊化红磷(MRP)、氰尿酸三聚氰胺(MCA)、磷氮复合阻燃剂(ZR3)以及含硅有机阻燃剂(ASBP)等不同的阻燃协效剂协同阻燃氢氧化镁,考查了MRP含量对氢氧化镁的协同阻燃效果、MCA和MRP物理复配的比例对氢氧化镁的协同阻燃效果、以及四种不同的阻燃协效剂分别对氢氧化镁协同阻燃效果的影响。研究结果表明:MCA对于复合材料断裂伸长率的恶化最为严重,并且使得复合材料不能通过电缆材料的热延伸试验;ZR3对于复合材料拉伸强度的恶化最为严重;而用MRP和ASBP协同阻燃的复合材料具有优异的阻燃性能和力学性能,优良的耐高温老化性能和电学性能,并且ASBP能够有效改善复合材料的加工流变性能,制备的无卤阻燃硅烷交联POE复合材料满足电缆护套材料的工业化生产的要求,具有广阔的市场价值。
The rapid development of economy in our country brings out the rapid increase of demand of cable and wire in recent years, especially in the projects of rural electrical transportation and urban construction. The increase is not only reflected in the quantity, but also in the quality. In the RoHS directive, some hazard substances, including some halogen-containing flame retardants and heavy metals, are strictly limited in the use of electrical equipment and appliance. So the toxic-containing cable materials will retreat in the market gradually. In spite of PVC cables using by now, halogen-free cables have been becoming a big market and the environment-friendly cable materials with high quality will be a new topic in research.
POE is a kind of non-polar material with saturated molecular chains, and therefore exhibits good electrical properties, resistance to oxygen and ozone, as well as high-temperature aging resistance. All these properties lead POE to be suitable for application in the cable as sheath jacket materials to replace PVC, Chloroprene Rubber, Chlorosulfonated Polyethylene. And there is a good prospect in application.
In this paper, we have used silane-crosslinked POE as matrix, magnesium hydroxide as a major halogen-free flame retardant, EVA as compatibillizer, and MRP, MCA, ZR3, ASBP as synergistic flame retardant, to develop a kind of halogen-free silane-crosslinked cable material, which exhibits excellent mechanical properties and flame-retardant performance, good electrical properties and processing performance, and high-temperature aging resistance. Firstly, we studied the effect of MH content on flame-retardancy, tensile properties, electrical properties, hot set test, as well as high-temperature aging resistance of the composites. The results showed that the composite with 140phr MH as flame retardant exhibited excellent mechanical properties and flame-retardant performance, good electrical properties and processing performance, and high-temperature aging resistance, and could pass the hot set test. Secondly, we studied the effect of EVA content as compatibillizer between XPOE and MH. The results showed that high-temperature aging resistance and elongation at break were greatly improved when 10phr EVA was added as compatibillizer in the composite, which exhibited excellent flame-retardant performance and could pass the hot set test. Finally, we used MRP, MCA, ZR3 and ASBP as synergistic flame retardant with MH and studied synergistic effect of the content of MRP, MCA ratio in blends of MRP and MCA, and the four different flame retardants individually with 2phr in amount on the properties of the composites. The results showed that the composite with MCA was seriously deteriorated in the elongation at break and couldn’t pass the hot set test, while the tensile strength of the composite with ZR3 was badly lost. And the composites with MRP or ASBP exhibited excellent mechanical properties and flame-retardant performance, good electrical properties and processing performance, and high-temperature aging resistance, and could pass the hot set test, which can meet the demand of sheath jacket materials in production and are promised a broad market value.
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