The effect of the interior particle structure of PVC suspension resin on the behavior of plasticizer absorption

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Abstract
In the suspension polymerization of vinyl chloride, halting at low conversions and polymerizing with certain organic chemical additives in the reactor recipe result in resins that exhibit somewhat faster plasticizer absorption behavior. By fitting vinyl chloride monomer sorption rate data for some specially prepared suspension resins to a Fickean diffusion model, the effective diameters of sorbing sphere structures in resin grain interiors were measured and were identified as groups of primary particles knitted together into compact 3-μm agglomerates. Good correlation between these measured agglomerate diameters and the reduction in plasticizer dry times, which were induced either by lowered conversion or increased use of an organic chemical additive during polymerization, led to the conclusion that these polymerization variables achieve their effects primarily by reducing the size of the agglomerates.