聚合物基层状双氢氧化物和氢氧化镁纳米复合材料的研究

【作者】 邱龙臻；

【导师】 瞿保钧；

【作者基本信息】 中国科学技术大学 ， 高分子化学与物理， 2006， 博士

【摘要】 随着环境保护和火灾安全意识的不断增强，金属氢氧化物（MH）作为聚合物无卤无磷消烟型阻燃剂正受到越来越多的重视。但由于MH的阻燃效率低，在聚合物阻燃材料中的填充量大，致使材料的力学性能变差，严重影响了其应用。在结构和成分上非常类似于金属氢氧化物的层状双氢氧化物（LDH）是最近发展起来的令人关注的新一类聚合物无卤无磷消烟型多功能无机阻燃剂。本论文应用层状双氢氧化物和纳米氢氧化镁制备了聚合物／无机纳米复合材料，研究发现这类纳米复合材料具有良好的热稳定性和阻燃性能，有望发展成为一种对环境友好的、易于加工成型的、低烟无卤无磷无毒清洁型兼有纳米阻燃和力学增强增韧的新型高分子复合新材料。本论文工作的主要创新点包括： 1．采用溶液插层方法制备了聚苯乙烯（PS）／ZnAl LDH纳米复合材料。研究了制备条件对纳米复合材料结构的影响和有关性能。结果表明：通过降低ZnAl LDH的含量，延长回流时间和应用快速沉淀法可以获得完全层离的PS／ZnAl LDH纳米复合材料。PS／ZnAl LDH纳米复合材料的热氧化降解速度远低于纯的PS。以50％失重处作为比较点，纯PS和Zn₃Al-DS含量为5％、10％和20％的PS／Zn₃Al LDH纳米复合材料样品的热降解温度分别为350、380、389和367℃。通过比较不同结构纳米复合材料的TGA结果发现层离结构的纳米复合材料比插层结构纳米复合材料具有更好的热稳定性。 2．应用α-溴代正丁酸插层的Zn₃Al层状双氢氧化物来引发苯乙烯单体进行原子转移自由基聚合（ATRP）反应，原位制备了PS／Zn₃Al LDH纳米复合材料。XRD和TEM的结果表明由ATRP所得的纳米复合材料为层离型结构。TGA测定的数据表明：如果以50％失重为比较点，层离型的聚苯乙烯／Zn₃Al LDH纳米复合材料的热降解温度比纯聚苯乙烯高出了45℃。 3．研究了用无皂乳液聚合法一步制备了层离型PS／Mg₃Al LDH纳米复合材料，并用XRD和TEM方法观测了制备过程中LDH的层间距和形貌的变化特征。由于该制备过程中没有使用小分子量的表面活性剂，所得PS／LDH纳米复合材料的起始热降更多还原

【Abstract】 Metal hydroxides as smoking- and toxic-free additives have been extensively used in halogen-free flame-retardant polymeric materials. However, their fatal disadvantages are low flame-retardant efficiency and thus very large usage amount is needed to meet the flame retardant requirement, which lead the mechanical and processing properties of materials to drop down sharply. In this thesis, the polymer/metal hydroxides nanocomposites with layered double hydroxide (LDH) and nanosized magnesium hydroxide have been prepared by solution intercalation, in situ atom transfer radical polymerization (ATRP), and soap-free emulsion polymerizaiton, and characterized by XRD, TEM, TGA and dynamic FTIR etc. Because of their improved thermal stability and flame-retardancy, the obtained nanocomposites may be widely applied for halogen-free flame retarding polymeric materials. The novel results are as follows.1. Exfoliated PS/ZnAl LDH nanocomposites were prepared by a solution intercalation method. The XRD and TEM data show that the exfoliation of LDH in solution involve two steps of solvent swelling and layers broken processes during refluxing and thus affect the structures of resulting nanocomposites. The completely exfoliated nanocomposites can be achieved by decreasing the content of LDH, elongating the refluxing time, and rapid precipitation method. The TGA profiles of PS/ZnAl LDH nanocomposites show a significantly enhanced thermal stability compared with pure PS. The PS/LDH nanocomposites with 10 wt% ZnAl(DS) have the best thermal stability. Its thermal decomposition temperature is 39℃ higher than that of pure PS. The thermal stability of the exfoliated nanocomposites is better than that of intercalated nanocomposites.2. Exfoliated PS/LDH nanocomposites were achieved by in situ ATRP reaction from α-bromobutyrate modified LDH. The thermal stability of the nanocomposites shows a remarkable improvement. When the 50 wt % weight loss is selected as a comparison point, the thermal decomposition temperature of PS/LDH nanocomposites is about 45 °C higher than that of pure PS.3. Exfoliated PS/LDH nanocomposites were obtained by soap-free emulsion polymerization method without the aid of any surfactant. The XRD and TEM determinations have been used to monitor the changes of interlayer spacing and更多还原