The aim of this study is to obtain experimentally a set of reliable interfacial tension data regarding polar/polar and non-polar/polar blends of polyethylene glycol (PEG) with olefinic copolymers and to compare to theoretical values. Indeed, the bibliographical study has revealed a lack of information on the matter. It is worth studying the effects of polarity and viscosity on the interfacial tension values when considering the morphology of blends based on viscoelastic matrixes with very low viscosity ratios. In this context, two viscoelastic polymers were selected as matrix to investigate the effect of polarity: a non-polar branched polyethylene copolymer, and a polar ethylenevinylacetate copolymer (EVA). The Newtonian dispersed phase was chosen so that the viscosity ratio could be varied in a series of alcoholic species either polymeric PEGs, with various molecular weights ranging from 20000 g/mol to 400 g/mol, or low molecular weight liquids (glycerol, ethylene glycol) or water. The interfacial tension values were obtained using 3 different methods: Interfacial tension values were calculated using Fowkes equation and data of surface energy found in the literature. These interfacial tensions were also obtained indirectly from rheological measurements, carried out on blends and using the Palierne's model. Finally, they were measured directly by droplet relaxation after a small deformation. Drop retraction was observed with a rheo-microscope. All data were collected for different systems, viscosity ratios and temperatures allowing a better understanding of the influence of these parameters on blend morphologies, and completing the literature for low viscosity ratios.