纳米氢氧化镁/橡胶复合材料的分散特性及分散机理

以新型的纳米氢氧化镁粉体为分散相研究对象,通过扫描电子显微镜、透射电子显微镜、Payne效应等考察了其在丁腈橡胶、三元乙丙橡胶、丁苯橡胶、硅橡胶中的分散相态和网络结构。结果表明,基体的粘度和表面能对纳米粉体最终的分散状态和网络结构有至关重要的影响。基体的粘度和表面能越高(NBR、EPDM),纳米粉体分散越精细,越容易形成柔性的网络结构,高分子参与比重很大;而在很低粘度和表面能的基体中(硅橡胶),纳米粉体以孤立的大聚集体形式存在,在低填充量下,不能形成网络结构,但在高填充量时,反而由大聚集体直接连成刚性很高的网络结构,高分子参与网络结构形成的程度小。传统的模型不能全面地考虑各种主要因素对粉体聚集体所受外力的影响,本文中提出了一个修正的模型来引入表面能因素的影响。

DISPERSION STRUCTURE AND MECHANISM OF THE NANO-MAGNESIUM HYDROXIDE/RUBBER COMPOSITES

A novel nano-magnesium hydroxide powder was chosen as a dispersion phase material and mixed with nitrile rubber(NBR), ethylene-propylene-diene mischpolymer (EPDM), styrene-butadiene rubber(SBR) and silicone rubber(SiR) to make a series of composites. By scanning electronic microscopy (SEM), transmission electronic microscopy (TEM) and Payne effect, the dispersion morphology and network structure of the composites were investigated in detail. The experimental results indicate that viscosity and surface energy of the matrix play very important roles in dispersion and network forming of nano-powder in rubber. The higher the viscosity or surface energy (EPDM, NBR) of the matrix, the finer the dispersion of nano-powder, and the more easily the network forms. The network is flexible due to the large proportion macromolecules involved. But in the rubber (SiR) with low viscosity and surface energy, there exist isolated agglomerates, not forming network in the low loading condition, while in the high loading condition the rigid network is formed by direct contacting of agglomerates, and the proportion of the macromolecule in the network is low. Traditional models can not describe the effect of main factors on the force on the agglomerates; a new modified model is proposed to introduce the effect of surface energy of the matrix.