Multiscaling Approach for Non-Destructive Adhesion Studies of Metal/Polymer Composites

The adhesion of polyamide 6 (PA6) and polyethylene (PE) toward an aluminum alloy (Al-A) and a dual phase steel (DPS) is studied by contact angle (CA) measurements and atomic force microscopy (AFM). With the combination of the two methods the adhesion properties on a macro- and (sub)microscopic scale can be determined in a nondestructive way. The work of adhesion per area (Wad) of the studied metal/polymer hybrids qualitatively scales the same on both length scales, that is, Al-A/PA6 > DPS/PA6 > Al-A/PE, DPS/PE. The polymer dominates the adhesion. The lower adhesion for PE toward the metal surfaces is explained by dominating van der Waals attraction forces, whereas adhesion for PA6 can also be attributed to attractive polar forces such as hydrogen bonding. For metal/PA6, Wad on a macro- and microscopic length scale is similar. For metal/PE, a discrepancy is measured with lower adhesion values on the microscopic scale than on the macroscopic scale.