AbstractIn the suspension polymerization of VCM insoluble polymer particles are formed inside the vinyl chloride monomer droplets. The nucleation, growth and aggregation of these particles are responsible for the internal morphology and associated properties (i.e. surface area, pore size distribution) of the particulate PVC product. The objective of the present study is to develop a microscopic particle morphology model that can predict the dynamic behaviour of the primary particle size distribution in terms of the controlling process variables (i.e. temperature, initiator concentration, etc.) by formulating a population balance equation to follow the time variation of the primary particle density function from the point of nucleation of basic particles to the formation of particle aggregates. It is shown that model predictions of the primary size distribution are in very good agreement with experimental observations.