【作者】 梁勇；

【导师】 李三喜；

【作者基本信息】 沈阳工业大学 ， 应用化学， 2010， 硕士

【摘要】 随着人们对环境保护的高度重视,在评价、选择聚乙烯等聚烯烃材料性能时,除了考虑其阻燃性能外,低毒、低烟也是聚烯烃材料必不可少的指标。氢氧化镁是一种具有无毒、低烟、热稳定性好等优点的环保型无机阻燃剂,由于其表面呈亲水性,而聚乙烯表面呈疏水性,需要对氢氧化镁进行表面改性以改善其表面物理化学性质,增强其与聚乙烯材料的相容性,还需要提高阻燃聚乙烯复合材料的机械性能等。采用干法处理工艺对氢氧化镁进行表面改性,考察了改性温度、改性剂用量和改性时间对氢氧化镁的活化指数的影响,结果表明,提高改性剂温度、增加改性剂用量和改性时间均可以提高氢氧化镁的活化指数。确定氢氧化镁改性的最优条件为：改性温度控制在80℃,改性剂硬脂酸镁和KH570的用量分别为待改性氢氧化镁粉体质量的2.5%、0.5%,改性时间达到3h。FTIR、XRD和SEM结果表明改性后的氢氧化镁的活化指数高达98%以上、粒子极性得以降低、分散性得到明显提高。文中也对氢氧化镁/硼酸锌复合体系的改性进行了初步研究。将最优条件下改性前后的氢氧化镁与聚乙烯制成共混体系,随着氢氧化镁添加量的增加,氢氧化镁/聚乙烯共混体系的拉伸强度呈下降趋势,在添加量为20%时,与纯聚乙烯材料相比,改性前后氢氧化镁/聚乙烯共混体系的拉伸强度分别下降了8.22%、1.98%。氢氧化镁/聚乙烯共混体系的LOI值随着氢氧化镁添加量的增加逐渐增大,添加量为35%时,改性前后氢氧化镁/聚乙烯共混体系的LOI值分别为26.0、24.6。DSC、TGA和SEM结果表明改性氢氧化镁/聚乙烯共混体系相比未改性氢氧化镁/聚乙烯共混体系具有更好的热稳定性、加工性能且与聚乙烯基体有更好的相容性。将最优条件下改性的氢氧化镁/硼酸锌复合体系与聚乙烯制备共混体系,在阻燃剂添加量为35%的情况下,改变氢氧化镁与硼酸锌的配比时阻燃聚乙烯材料的拉伸强度保持在19.0-20.6MPa之间；适当调整硼酸锌的比例阻燃聚乙烯的氧指数仍保持在25.0左右且阻燃聚乙烯的加工性能和热稳定性得以提高,SEM结果表明改性后氢氧化镁/硼酸锌复合体系与聚乙烯基体具有较好的相容性。更多还原

【Abstract】 With the increasing attention to environmental protection, low toxicity and low smoke have become important factors in evaluating the flame retardant properties of polyethylene materials and other polyolefin. As the surface of magnesium hydroxide and polyethylene is hydroophilic and hydrophobic, respectively, surface modification of magnesium hydroxide is necessary to improve the surface physical and chemical properties and to enhance its compatibility with the polyethylene material, as well as to maintain the mechanical properties of flame-retardant polyethylene, and so on.In this study, the dry process modification of magnesium hydroxide was conducted. The effects of modification temperature and the amount of modification agents and modification time on activation index of magnesium hydroxide have been studied. It’s found that the activation index of modified magnesium hydroxide increases with the increasing of modification temperature and the amount of modification agents and modification time. The optimal modification conditions for magnesium hydroxide are modification temperature is controlled to be 80℃, the modifier amount of magnesium stearate and KH570 compared to the weight of modified magnesium hydroxide powder is 2.5% and 0.5%, respectively, and the modification time is 3h. The activation index of magnesium hydroxide powder modified in optimal modification conditions reaches 98% or more. It’s found from FTIR, XRD and SEM that particle polarity of magnesium hydroxide modified has been reduced and dispersion of powder has been obviously improved. In this paper, the modification of magnesium hydroxide/zinc borate compound system has also been studied.The modified magnesium hydroxide and polyethylene have been blend together. With the increasing addition of magnesium hydroxide, the tensile strength and the LOI value of magnesium hydroxide/polyethylene composites have been decreased and increased, respectively. When content of magnesium hydroxide is 20%, the loss tensile strength of modified magnesium hydroxide/polyethylene composites and unmodified magnesium hydroxide/polyethylene composites is 8.22% and 1.98%, respectively. When content of magnesium hydroxide reaches 35%, the LOI value of modified magnesium hydroxide/ polyethylene composites and unmodified magnesium hydroxide/polyethylene composites is 26.0 and 24.6, respectively. It’s found from the result of DSC, TGA and SEM of tensile fracture that modified magnesium hydroxide has more good thermal stability, processing properties and has better compatibility with polyethylene composites.In this study, the compound system of magnesium hydroxide and zinc borate has been blend with polyethylene. When the amount of flame retardant reaches 35% of the total mass of the composite, with the change of ratio between magnesium hydroxide and zinc borate the tensile strength of flame retardant PE change from 19.0 Mpa to 20.6MPa. With the ratio of zinc borate appropriate adjustments, the LOI value of blends remained at 25.0 or so. It’s found from SEM and other tests that the properties of process and thermal stability of polyethylene have been effectively improved and the retardant particles has better compatibility with the matrix of polyethylene.更多还原