The work focuses on understanding the mixing of low viscosity fluids in molten polymers, i.e. with components with a large difference in viscosity. The idea is to complete de Grace curve for low viscosity ratios and to understand the effect of polarity on the dispersion. Mixing of fluids is not well understood but is largely used in industrial processes such as a monomer in a high viscosity polymer or yet the use of water as a carrier for blending small-sized carriers. To this end, two olefinic copolymers with low crystallinity rates were chosen as matrixes and a range of PEG with various molar masses were used at first as polar dispersed phase. Finally, ethylene glycol, glycerol and water were also dispersed in the matrixes. Droplet sizes were calculated in equilibrium conditions. Special care was taken to work at dispersed phase concentrations sufficiently low to prevent coalescence. Interfacial tension was a crucial parameter in determining the critical capillary number and was therefore carefully determined through theoretical, semi experimental and experimental methods. Critical capillary numbers for each blend were calculated and compared to the Grace Curve.