填充补强剂在橡胶基质中分散状态的研究

将透射电子显微镜 (TEM)与扫描电子显微镜 (SEM )结合在一起, 系统观察了氧化锌、碳酸钙、陶土、粘土、炭黑、白炭黑等填料在丁苯橡胶中的分散状态,也考察了粘土 /橡胶纳米复合材料中粘土晶层的分散情况。发现各种填充补强剂在橡胶中均存在着几种层次的分散结构,混炼过程会进一步粉碎粒子,粉碎程度的大小依赖于分散相的内聚强度和结构特征。直接混炼也会造成粘土晶层一定程度的剥离,从而在基质中产生一些纳米尺度的分散质。大多数纳米复合材料包括原位聚合制备的纳米复合材料中,分散相都存在着一定程度的聚集体,不可能达到理想的均匀的分散,含量越高,聚集体数目越多。分散相的界定依赖现有仪器的分辨率。据此,也重新给出了纳米复合材料的定义:只要在某一分辨率下,分散相粒子的尺寸至少应有一维≤100nm,同时其质量分数或体积分数应达到 80 %以上。并认为炭黑和白炭黑增强的橡胶均属于纳米复合材料。

Research on dispersed states of the bulking and strengthening agents in the rubber matrix

The dispersed states of ZnO, CaCO 3, argil, clay, carbon black and carbon white in SBR matrix were characterized by electronic microscope TEM and SEM. To make a comparison with the above, the dispersed states of clay/rubber nanocomposites were studied and compared with that of clay/PMMA nanocomposite. According to TEM and SEM photos, there are several levels of dispersed structure with different dimension. Mechanical intermix of rubber contributes to the further fragmentation of the dispersed particles. The further fragmentation of the dispersed particles depends on the cohesion and structural feature of the dispersed phase. Especially, just direct mechanical intermix can in some degree induce fragmentation of clay particles to form some nanodimension dispersed particles. There, however, is no way to form ideally uniformly dispersed nanocomposite. In most nanocomposites besides nanocomposites prepared by in situ polymerization, there are some congeries. The more the loading amount of dispersed phase leads to the more amount of congeries. The definition of the dispersed phase depends on the resolution of the instrument. A new definition of nanocomposite, therefore, was put forward. If in certain resolution, the dimension of dispersed particles which was less than 100nm and these particles have more than 80 percent by weight or by volume of all the dispersed phase, this materials is nanocomposite. From the point of this view, the rubber strengthened by either carbon black or carbon white involved in this paper was nanocomposites.