A simple technique for measuring particle size distributions during suspension polymerization

The techniques actually available for the measurement of particle size dist ributions are mainly used for liquid-liquid or solid-liquid dispersions in non-reactive systems and there is a lack of experimental data for the dynam ics of these distributions under reactive conditions. In the case of suspen sion polymerization this is mainly related to the optical properties of the reaction medium and to the difficulties inherent in the measurements of pr operties which rapidly change with time. In this paper a new procedure is d escribed to measure the dynamics of particle size distributions during the course of a suspension polymerization. This technique is based on the abili ty of an agarose solution, when mixed with a sample of the polymerizing sus pension, to transform it into a gel, thereby freezing its morphology. The p olymerization can thus be completed under "static'' conditions, that is wit hout breakage and coalescence events, and the measurements can be performed in a conventional way for solid particles. The procedure is very simple an d can be applied to any process with water as suspending agent. As an examp le experimental data are shown for the batch suspension polymerization of m ethylmethacrylate carried out in different operating conditions.