This work analyzes the dispersion conditions of polar liquids with low viscosities into polymer melts. For this purpose, the curve of the critical capillary number in shear as a function of the viscosity ratio for low viscosity liquids dispersed into polymer melts was built. To obtain this curve, the disperse phase and matrix were chosen to have large polarity and viscosity differences (viscosity ratio between 10(-7) and 10(-2)). To this end, polyethylene glycols with various molecular weights, ethylene glycol, glycerol or water were mixed with olefinic copolymers in an internal mixer assumed to generate mostly shear. Concentrations of dispersed phase were low enough to prevent coalescence. In combination with viscosity data and measured interfacial tension, the critical capillary number was calculated from the droplet size in equilibrium conditions and the variation with viscosity ratio was compared with theoretical equations from the literature. (C) 2016 The Society of Rheology.