Polymer Layered Double Hydroxide And Magnesium Hydroxide Nano-composite Materials

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...