The powder suspension polymerization process

The powder suspension polymerization is the most important polymerization process for manufacturing PVC. The main advantage of this process is that large (e.g., 300-500 pm). 

As a result of the above mechanism, the polymerizing VCM droplet loses its viscous characteristics at relatively low monomer conversions, while at larger monomer conversions (i.e., X 30%) it behaves like a rigid sphere due to the presence of the continuous polymer skeleton. In fact, above a critical monomer conversion (i.e., x 30%) the volume contraction of the polymerizing particles stops, which partially explains the appearance of internal particle porosity. Note that the polymer density is approximately 40% higher than the monomer density. 

It should be noted that the utihzation of a reflux condenser for heat removal in the VCM suspension polymerization introduces some operational problems. For example, noncondensable gases maybe concentrated in the condenser, which can reduce its heat removal capacity. The level of non-condensable gases in the reactor vapor phase will depend on the quality of the monomer, how well the reactor has been evacuated prior to polymerization and whether or not the polymerization process generates inert gases [20]. For example, the use of azo initiators will result in the formation of nitrogen as a byproduct of the initiator 

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