AbstractThis paper focuses on the calculation of the interfacial tension of two systems: low‐density polyethylene with isotactic polypropylene and high‐density polyethylene with syndiotactic polypropylene. For this, three methods to measure the interfacial tension are compared: the use of Palierne's model, and Gramespacher and Meissner's model, both based on additional elasticity or long relaxation times brought by shape recovery of dispersed phase, and ab‐initio calculation, which requires the knowledge of the surface tension of the neat polymer measured at the same temperature. For that, a database collected from the literature is built in the first section of this paper, whether for the studied systems or for other systems of various olefinic homopolymers or copolymers with polypropylene. The results show the effectiveness of the Gramespacher and Meissner's model to calculate the interfacial tension of the studied systems for which the results were in agreement with ab‐initio calculation and Palierne's model. Extension of the ab‐initio calculation to olefinic copolymers was proposed.