An analysis of the origin of coalescence suppression in compatibilized polymer blends

The course of the flow-induced coalescence and the effects of the Marangoni force and steric repulsion on the coalescence suppression in polymer blends containing a compatibilizer were analysed. The expression for coalescence probability of deformable droplets, reliably describing its dependence on the droplet size, was proposed. It was shown that a strong negative correlation exists between the Marangoni force and steric repulsion contributions and the decisive mechanism of the coalescence suppression cannot be determined from the dependence of coalescence on the shear rate. For prediction of the magnitude of the Marangoni force, the knowledge of the rate of copolymer diffusion along the interface is necessary. The influence of simultaneous collisions of three and more droplets and of droplet deformation in flow, which are not included in available theories, is discussed.