EFFECT OF POLYTETRAFLUOROETHYLENE PARTICLES ON THE FOAMABILITY OF AQUEOUS SURFACTANT SOLUTIONS

It has been shown that the presence of PTFE particles may reduce the amount of foam which can be generated by vigorous shaking of surfactant solutions. PTFE is an inert and hydrophobic material. The experiments have therefore demonstrated that the formation of destabilizing surface tension gradients is not a necessary condition for antifoam behavior. Simple calculations have demonstrated that particles of hydrophobic material present in thin films may in principle spontaneously dewet to form a hole which would necessarily lead to film rupture. The critical condition for hole formation is shown to be dependent upon contact angle and particle shape. Particle size is an implicit consideration in that the smallest dimension of the particle must be approximately equal to the film thickness before hole formation can occur. This antifoam mechanism is shown to be consistent with all the experimental observations concerning the effect of PTFE particles on the foamability of surfactant solutions. © 1979.