Evaluation of dispersion of nano-CaCO3 particles in polypropylene matrix based on fractal method

Nanometer calcium carbonate (nano-CaCO3) filled polypropylene (PP) composites were prepared respectively by using two surface treatment methods of filler particles (named SI with surface activation and named SII with titanate coupling agent) in this paper. The dispersion of the nano-CaCO3 particles in the PP matrix was observed by means of a scanning electron microscope (SEM), and the dispersion effect or formation was preliminarily evaluated by applying a fractal model based on statistic meaning from these SEM pictures. The results showed that the dispersion of the nano-CaCO3 particles in PP matrix was more homogeneous when the fractal dimensionality was less than about 1.5. In addition, the smaller the fractal dimensionality, the better the dispersion of the particles in the matrix was, within a certain limit. Under the same conditions, the dispersion of SII system was better than that of SI system.