Effect of polymerization conditions on the melt rheological properties of vinyl chloride–vinyl acetate copolymers

Abstract

SynopsisMathematical models have been developed which predict the composition, molecular weight, and melt rheological properties for vinyl chloride/vinyl acetate copolymers of inherent viscosity range 0.4-0.7 dL/g and bound vinyl acetate levels of 3.%17.4%. The effect of polymer long chain branching on the viscous/elastic moduli ratio is discussed as well as the comparison of Tinius-Olsen melt index measurements vs. mechanical spectrometer results. The reactivity ratio for vinyl chloride/vinyl acetate comonomer pairs was remeasured and found to be significantly different from literature values.

Free‐Radical Polymerization: Suspension

“…That is not often possible but models that allow for water solubility of monomers have been developed for the copolymerization of vinyl chloride and vinyl acetate [8] and for the copolymerization of styrene and acrylonitrile [9]. However, the use of those relationships is not straightforward if one, or more, of the monomers is partially soluble in the continuous phase, because the actual composition of the drops may then be unknown.…”

Physical properties of vinyl chloride‐propylene copolymers

“…The predictive equation includes both polymerization temperature and pressure rise terms, which were not important in the study of vinyl chloride-vinyl acetate study. 4 The bound propylene level decreases with increasing polymerization temperature K , because of the relatively low boiling point of propylene (-43°C); the higher the polymerization temperature the more propylene (relative to vinyl chloride) is driven into the vapor space and therefore out of the liquid phase where the polymerization occurs. The higher conversion K , results in a decrease in the expected bound propylene level.…”