The influence of different surface morphologies and compatibilizers on the bonding strength between high-density polyethylene (HDPE) and isotactic polypropylene (iPP) is determined by T-peel tests. To optimize the relative comparison, the polymer foils are prepared to have distinct areas with different bond strengths. The advantage of this comparative method is the observation of significant differences of the bonding strength within a single sample, eliminating such sensitive parameters as the dimensions and peel angle.