Regularities of the formation of polystyrene hollow microspheres

Abstract

The effect of different factors on the formation of hollow microspheres in the process of foaming of suspended polystyrene granules has been investigated at temperatures close to the boiling point of the foaming agent. It is shown that the non-isothermal kinetics of foaming are identical in character to the thermomechanical curves, and critical sizes of initial particles, at which a polycellular structure is formed, have been determined. It was found that these critical particle sizes depend on the diffusion coefficient of the foaming agent, and that as a rule a higher diffusion rate leads to an increase in the critical size of granules, and to increased probability of the formation of monospheres. The data obtained are analysed mathematically, and a set of equations is derived where by kinetic regularities of the foaming of polystyrene granules by liquid foaming agents are described.