ABSTRACT High density polyethylene (HDPE), linear low density polyethylene (LLDPE) and low density polyethylene (LDPE) are blended, and compared against a similar mixture but functionalized LDPE with maleic anhydride (MAh), HDPE‐LLDPE‐LDPE‐g‐MAh. In order to obtain nanocomposites from these polymer blends, a modified bentonite was added by incorporating l‐lysine into the bentonite galleries by melt extrusion. The resulting nanocomposites presented improved mechanical properties linked to strong polymer‐bentonite interactions and exfoliated structures as verified by transmission electron microscopy and rheometry. A detailed analysis of the feasible polymer‐bentonite interactions was conducted, of particular concern between the polar MAh groups and the intercalated l‐lysine. To gain further insights into the type of molecular interactions (i.e. polymer‐bentonite), a model nanocomposite was synthesized in solution to carry out further assessments through NMR, infrared spectroscopy and rheology analysis. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46920.