Shear‐induced coalescence in two‐phase polymeric systems. I. Determination from small‐angle neutron scattering measurements

It has been found that flow‐induced coalescence occurs at a very rapid rate during the mixing of polymeric fluids. Furthermore, the rheological properties of the dispersed and continuous phases, as well as the nature of the flow field used in their blending, can greatly influence this coalescence. The significance of these findings is that in the development of a mixing scheme to obtain a desired morphology with minimum expenditure of time or energy, attention is usually focused only on the particle breakup aspects of the blending process. The competing coalescence can, however, be accelerated by the same conditions often employed to facilitate particle breakup (e.g., higher shear rates, reduced dispersed‐phase viscosity). A better understanding of the mechanism for coalescence of viscoelastic fluids is clearly required. In this manner optimal blending of immiscible polymers can be achieved with respect to both the nature of the final material and the ease with which it is obtained.