A study on polymer blending microrheology

In this paper it is shown that the formation and subsequent breakup of threadlike particles are important disperging mechanisms and largely govern the morphology resulting from a polymer blending process. Experiments on the breakup of Newtonian threads surrounded by a second Newtonian fluid have been carried out and good agreement with Tomotika's theory is achieved. Experiments on the breakup of viscoelastic fluid threads showed the influence of shear thinning and stretch thickening effects of the fluids used. To investigate the influence of non‐Newtonian behavior of molten polymers on capillary instabilities, experiments were carried out on the breakup of molten polymer threads embedded in a second polymer melt. Surprisingly an absence of shear thinning and stretch thickening effects was noticed and good agreement with Tomotika's theory was obtained. Finally, the stability of threads of fluids exhibiting a yield stress was studied. A criterion predicting the stability of such threads was established and verified experimentally. On the basis of this criterion a possible explanation is given for the stability of a certain class of co‐continuous morphologies.