Abstract:

Two polymethyl methacrylate ammonium salts（MAPS-B and MAPS-O）were used to modify montmorillonite. Such thermally stable oligomerically modified montmorillonites were further melt-compounded with polybutylene terephthalate（PBT）at a high temperature and six kinds of nanocomposites（PBT/MAPS-B-1，PBT/MAPS-B-2，PBT/MAPS-B-3，PBT/MAPS-O-1，PBT/MAPS- O-2 and PBT/MAPS-O-3）were obtained. The influence of the structure and content of oligomerically modified montmorillonite on the morphology and properties of the nanocomposites were evaluated. The results of X-ray diffraction（XRD）and transmission electrical microscopy（TEM）indicated that the PBT/MMT nanocomposites had intercalated structures. Increased clay loading was a disadvantage for clay dispersion in the polymer matrix. Thermogravimetric analysis（TGA）showed that thermal stabilities of the PBT/MAPS-B and PBT/MAPS-O nanocomposites were improved remarkably. The onset temperature of thermal degradation（T_onset）of PBT/MAPS-O-2 was 20 ℃ higher than that of the pristine material. The thermal stability of the composites was influenced by the dispersity of clay. The poor dispersity with clay loading higher than 2% resulted in decreased T_onset of PBT/MMT. The effects of modified clays on the crystallization behavior of PBT were characterized by differential scanning calorimeter（DSC）. The results showed that the nanocomposites of polyester/MMT had higher crystallization rate and a little lower melting temperature than the pristine polyester. The crystallization rate increased with increasing MMT content.

摘要：

用聚甲基丙烯酸甲酯苄基季铵盐和聚甲基丙烯酸甲酯十八烷基季铵盐修饰蒙脱土，制备出两种有机土（MAPS-B-MMT和MAPS-O-MMT），通过熔融共混法制备聚对苯二甲酸丁二醇酯/蒙脱土（PBT/MMT）纳米复合材料，考察了有机土含量和修饰剂结构对复合材料性能的影响。TEM结果显示，两类复合材料均为插层型纳米复合材料。热稳定性能研究表明，PBT/MAPS-B和PBT/MAPS-O两个体系热稳定性有较大的改善，材料的初始降解温度均比纯PBT提高，PBT/MAPS-O-2纳米复合材料的初始降解温度提高了20 ℃；热稳定性受到蒙脱土分散性影响，随着黏土含量增加，蒙脱土分散性变差，导致材料初始降解温度下降，质量分数2%为蒙脱土的最佳含量；加入有机土降低了材料的熔融温度，提高了材料的结晶速率和结晶度。