The paper deals with the synthesis and characterization as polymer processing aids, i.e. as plasticizers and/ or lubricants, of some mixed (unsymmetrical) diesters of adipic acid by using aliphatic alcohols of variable length, such as C4, C6, C2-6, izo C10 and izo 03, along with complex aliphatic-aromatic alcohols, like 2-phenoxyethanol, 2-[(o-sec-butyl)phenoxy]ethanol and 2-[(p-nonyl)phenoxy]ethanol, respectively. The diesters derivatives obtained this way showed plasticizing and/or lubricating properties. The variation of such properties was studied by varying the polar/unpolar ratio within each structure of the considered product. Interesting correlations were recorded and the theoretical premises were fully proved.