【作者】 刘渊；

【导师】 贾润礼；

【作者基本信息】 中北大学 ， 材料学， 2007， 硕士

【摘要】 聚乙烯(PE)是热塑性塑料中的第一大品种,具有质轻、无毒、耐化学腐蚀性优异等特点,广泛应用于电器、化工、食品、机械等行业。但是聚乙烯的氧指数很低仅为17.5,属于易燃材料。聚乙烯在燃烧时,会产生严重的熔融滴落行为,这给其阻燃改性带来很大的困难。除易燃外,聚乙烯的体积电阻率和表面电阻率都很高,这就使其在加工和使用过程中一旦带上静电就很难消除。以上这两个缺点给聚乙烯的使用带来了很大的安全隐患。因此,对聚乙烯进行阻燃、抗静电(双抗)改性意义非常重大。对聚乙烯进行双抗改性时的难点除了上述聚乙烯的熔融滴落行为给阻燃带来的困难外,在阻燃改性和抗静电改性之间还存在着冲突。抗静电改性时所添加的助剂会对聚乙烯的燃烧起到促进作用,这就会使双抗改性时阻燃剂的添加量比单独阻燃改性时要大,而大量添加阻燃剂会导致材料的力学性能恶化、流动性变差等结果。目前,人们把阻燃的研究的重点都集中在了无卤阻燃上,但是无卤阻燃剂的效果远不如卤系阻燃剂,要达到同样的阻燃效果所需的添加量会很大,这就会带来一些的新问题,如力学性能恶化、材料流动性变差等。在这种情况下,采用复配阻燃这种新型技术路线逐渐成为近年来的研究热点。本论文在制备双抗改性聚乙烯的过程中,以氧指数法作为考查阻燃性能的指标,研究了所添加助剂对材料阻燃性能的影响;以体积电阻率和表面电阻率作为考查抗静电性能的指标,研究了碳纤维的添加量对材料抗静电性能的影响;以拉伸强度和缺口冲击强度为考查力学性能的指标,研究了所添加助剂对材料力学性能的影响。通过测试发现,受力学性能限制,单独添加聚磷酸铵无法制备阻燃聚乙烯材料,当其添加量达到30%时,材料的氧指数最高也仅有22.4,而通过与其它阻燃组分复配后,最终制备了氧指数最高达29.1的阻燃聚乙烯材料。在阻燃聚乙烯的基础上,通过向其中添加碳纤维,制备了多个配方的双抗改性聚乙烯材料,最后选出了氧指数高达27.5,体积电阻率和表面电阻率仅为5.6×1012?·cm和2.3×1012?的J2配方作为双抗改性较好的配方。本论文通过选用季戊四醇硬脂酰胺作为成炭剂,较好地解决了阻燃改性和抗静电之间的冲突。因为,季戊四醇硬脂酰胺一般作为偶联剂或润滑剂使用,本文选用它作为成炭剂,在保证材料阻燃性能的同时,又保证了材料较好的加工性能和力学性能。更多还原

【Abstract】 The yield of polyethylene is the biggest in the thermoplastics. Polyethylene has many distinguished features such as lightness, non-toxicity, resistance to chemical corrosion, and so on. It has been used widely in many industries such as electric industry, chemical industry, food industry, mechanical industry, and so on. Unfortunately, with low oxygen index (just 17.5), polyethylene belongs to combustible material. It is difficult to prepare flame-retarded polyethylene, because it’s dripping remarkably during the burning process. Except for low oxygen index, its volume resistivity and surface resistivity are pretty high. When polyethylene has been charged, it’s difficult to release the static charge. The two drawbacks of polyethylene endanger its safe use grievously. Take“safety”into consideration, flame-retarded modification and antistatic modification are needed urgently.In order to prepare both flame-retarded and antistatic polyethylene, two problems must be resolved. One is the dripping problem which has stated in detail. The other is the contradiction which exists between the flame-retarded modification and antistatic modification. Both flame-retarded and antistatic modification needs more content of flame retardants than the only flame-retarded modification, because the antistatic additives are combustion supporting materials. But massive content of flame retardants will lead to many other problems, such as poor mechanical properties, low flowing property, and so on.In recent years, non-halogen flame retardation of polyethylene has been investigated excessively. But the flame-retarded efficiency of non-halogen flame retardants is less than the halogen flame retardants. To achieve the same flame-retarded efficiency, more content of non-halogen flame retardants are needed compare to halogen flame retardants, and massive content of flame retardants will lead to other problems which were stated in detail. In this kind of situation, the new technical route that built flame-retarded system has been used to prepare flame-retarded polyethylene gradually.In this thesis, oxygen index was taken as the measurement to estimate the flame-retarded efficiency; volume resistivity and surface resistivity had been taken to estimate the antistatic efficiency after carbon fiber was added in; tensile-strength and notch impact-strength were taken as the measurements to estimate the mechanical properties. Some valuable results were discovered after tests. Firstly, flame-retarded polyethylene could not be prepared by only added APP in the polyethylene, because massive content of APP worsened the polyethylene’s mechanical properties markedly. Secondly, the oxygen index of polyethylene was only 22.4, when the content of APP reached 30%, but through new technical route, flame-retarded polyethylene whose oxygen index reached 29.1 was prepared at last. Thirdly, in the foundation of flame-retarded polyethylene, many batch formulas of both flame-retarded and antistatic polyethylene had been prepared. The batch formula of J2 was chosen as the optimum formula whose oxygen index reached 27.5, volume resistivity and surface resistivity declined to 5.6×1012?·cm and 2.3×1012? respectively.In this thesis dipentaerythritol stearamide was used as the charcoal source. The contradiction between the flame-retarded modification and antistatic modification was resolved by the dipentaerythritol stearamide. Because dipentaerythritol stearamide is generally used as coupling agent or lubricant, it has very little influence on the mechanical properties of polyethylene, and it has positive influence on the processing property of polyethylene.更多还原