The effect of surface treatment on the shear properties of aluminium-polypropylene joints manufactured by laser beam

In this article, we evaluated the mechanical response of laser-joined EN AW-6082 aluminium alloy and poly-propylene (PP) specimens under quasi-static and cyclic shear loading. In order to increase the strength of the joints, we formed grooves in the aluminium with laser ablation. We determined the effect of PP melt viscosity and heat generated during the joining process on the shear strength of the joints using three types of PP with different melt viscosities. In order to influence the adhesion between the apolar polypropylene and the aluminium, we also treated some PP specimens with maleic anhydride (MA) prior to joint formation. We found that by doing so, the quasi-static shear strength of the joints increased by 50% on average. Furthermore, when we engraved many grooves in the aluminium and treated the PP specimens with MA, the average failure cycle number of specimens could be increased by an order of magnitude.