Molybdate-based conversion treatment for improving the peeling strength between aluminum foil and polypropylene grafted with glycidyl methacrylate

• An environment friendly molybdate-based coating for aluminum was developed.
• The T-peeling strength of the molybdate treated foil increased about 10 times.
• The surface morphology of the Al foil after peeling was observed by SEM.
• The foil surfaces were characterized by SEM, AFM, EDS and contact angle.

This paper describes an environment-friendly treatment for aluminum (Al) foil that can greatly improve the adhesion strength between foil with the polymer film to a similar extent as the traditional chromate–phosphate treatment. Al foil was treated with different methods, after which a modified polypropylene (PP) film (PP grafted with glycidyl methacrylate, PP-g-GMA) was directly joined with the treated Al foil by hot pressing. The T-peeling strengths of the Al/PP-g-GMA composites were measured, and the peeling strength of molybdate-treated foil was found to be approximately 10 times greater than that of untreated foil. The surface morphologies of the Al foils were observed by scanning electron microscopy and atomic force microscope, their chemical compositions were characterized by energy-dispersive spectroscopy. The hydrophilicities and surface energies of the treated Al foils were further evaluated by contact-angle measurements.