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

/locate/compositesa Composites: Part A 38 (2007) 1502–1506Evaluation of dispersion of nano-CaCO3 particles in polypropylene matrix based on fractal method J.Z. Liang College of Industrial Equipment and Control Engineering, South China University of Technology, Guangzhou 510640, P.R. China Received 23 June 2006; received in revised form 21 December 2006; accepted 7 January 2007Abstract 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 dis- persion 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.  2007 Published by Elsevier Ltd. Keywords: Polypropylene; Nanometer-CaCO3; Composite; Fractal1. Introduction Polypropylene (PP) is extensively used in automobile and electronic appliance applications due to its good per- formance and processing properties as well as low cost. However, its application is somewhat limited due to its high shrinkage rate, and relatively poor impact resistance at room or low temperatures. Therefore, how to improve the impact toughness of PP resin has been extensively paid attention [1–3]. In general, the stiffness and dimen- sional stability of PP are improved significantly by filling with rigid inorganic particles which is widely used in industry, such as