Abstract
Well dispersion of nano-particles is necessary in order to bring out their unique properties, such as solubility, reactivity, and electromagnetic, optical and mechanical properties. However, it is difficult in general to disperse nano-particles homogeneously in liquid media because they are very prone to coagulate each other. In this study, we have developed and constructed a new apparatus for dispersing particles that basically consists of co-axial rotor and a static vessel to generate a high shear field between them. Coagulated particles are subject to high shear forces which enable to disperse the coagulated particles. In this paper we have firstly designed the dispersing apparatus, and have then carried out the dispersion tests with calcium carbonate particle which has tens nanometer size as a primary particle. The dispersion performance has been evaluated by measuring particle size distribution with taking account of shape of rotors, dimensions of the gap between rotor and vessel, rim speed of the rotor and operating time. It has been found that a smaller gap results in higher dispersing performance since higher velocity gradient is formed in the gap.
