Film deposition and consolidation during thin glove coagulant dipping

Abstract

In this article, we examine the rate of film build-up and the evolution of polymer volume fraction in coagulant dipped films. The results are for nitrile and natural rubber compounds. We describe a model for the build-up of a latex film that coagulates onto a former as a wet gel and consolidates by a wet sintering process. We achieve this by applying diffusion and reaction kinetics for the coagulant transporting from a former into the latex bath. Wet sintering, the underlying mechanism for serum exudation from the wet gel, is modelled for a consolidating aggregate of latex particles. The parameters used in the models are either measured in separate experiments or are available from the literature. We compare the model predictions with the experimental results. The first, rapid, stage of film build-up is modelled successfully by simple diffusion of the coagulant cations. At longer dwell times, it is found that the reaction between coagulant and surfactant is the primary mechanism for the rate reduction. The rate of consolidation of the wet gel could be modelled reasonably well using a previously developed equation for latex film formation. The rate was chiefly dependent on the stress relaxation modulus of the polymer.