Bertil Törnell

Swelling of PVC latex particles by VCM

Abstract The uptake of VCM by PVC particles prepared by emulsion polymerization at various temperatures, the solubility of VCM in water and the density of VCM vapour have been studied between 15 and 60°. The swelling of PVC by VCM was almost independent of temperature. The solvent interaction parameter, x , calculated according to the Flory-Huggins equation, was strongly dependent on polymer concentration and showed a maximum value. The maximum uptake of VCM depended on the temperature of polymerization. PVC samples prepared at 11, 50 and 90° showed maximum uptakes of 0.22, 0.29 and 0.37 kg VCM/kg PVC respectively. The influences of particle size and emulsifier concentration have been studied. The results indicate that VCM is solubilized in the surface layer of adsorbed emulsifier.

Flocculation of PVC Latex Particles in the Presence of Vinyl Chloride

A study has been carried out to elucidate the mechanism of a process by which a polyvinyl chloride (PVC) resin in powder form is obtained by flocculation of a PVC latex in the presence of liquid vinyl chloride monomer (VCM). The steps in the process were: n n1. n naddition of a flocculating polymer to the latex, n n n n n2. n naddition of VCM under thorough stirring, and n n n n n3. n nevaporation of VCM.