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A Simple Technique for Measuring Particle Size Distributions during Suspension Polymerization

The techniques actually available for the measurement of particle size distributions are mainly used for liquid-liquid or solid-liquid dispersions in non-reactive systems and there is a lack of experimental data for the dynamics of these distributions under reactive conditions. In the case of suspension polymerization this is mainly related to the optical properties of the reaction medium and to the difficulties inherent in the measurements of properties which rapidly change with time. In this paper a new procedure is described to measure the dynamics of particle size distributions during the course of a suspension polymerization. This technique is based on the ability of an agarose solution, when mixed with a sample of the polymerizing suspension, to transform it into a gel, thereby freezing its morphology. The polymerization can thus be completed under “static” conditions, that is without breakage and coalescence events, and the measurements can be performed in a conventional way for solid particles. The procedure is very simple and can be applied to any process with water as suspending agent. As an example experimental data are shown for the batch suspension polymerization of methylmethacrylate carried out in different operating conditions.