PVC paste rheology: Study of process dependencies

Abstract

A plastisol is a dispersion (suspension) of fine particles of poly(vinyl chloride) with a plasticizer that is normally applied over a substrate, by spreading or coating, before the gelification and fusion into the final product. Because of the first step, the plastisol rheology study is a very important factor which has to be taken into consideration to determine and fine tune the process conditions. This work is concerned with the study of the rheology of plastisols from selected PVC samples produced by the emulsion process, correlating it with the particle size distribution and surface characteristics from the polymer's powder and modifications during the plastisol aging process. The results obtained show a significant influence of the original polymer properties in the viscosity aging and viscoelastic behaviour of the plastisol. First, a significant decrease in viscosity can be achieved by changing a particular surfactant during the polymerization step. Second, the type of particle aggregates present in the powder, can determine the evolution of the particle size in the plastisol which, in turn, correlates directly with the observed modifications in the aging and viscoelastic behavior