Tribological Behavior of Polypropylene–Multilayer Plastic Waste Blends Under Two‐Body and Three‐Body Abrasion

ABSTRACT Multilayer plastic (MLP) poses significant recycling challenges due to its heterogeneous composition. This study evaluated the effect of MLP and polypropylene grafted with maleic anhydride (PP‐g‐MA) on the morphology, processability, mechanical properties, and tribological behavior of polypropylene (PP). MLP, consisting of oriented PP, metallized polyethylene terephthalate, and linear low‐density polyethylene, was incorporated at 5–15 wt.%, while PP‐g‐MA was added at 3 and 6 wt.%. Blends were characterized by scanning electron microscopy (SEM), melt flow index (MFI), tensile testing, hardness, and ball‐cratering wear tests under two‐body and three‐body abrasion. SEM revealed a typical immiscible blend morphology, while increasing PP‐g‐MA improved phase dispersion by reducing dispersed‐domain size and particle pull‐out. MLP increased MFI relative to PP, although it gradually decreased with increasing MLP content. Hardness remained essentially unchanged, whereas tensile properties improved, with increases of up to 28% in elastic modulus and 41% in tensile strength. Tribological performance also improved under both abrasive conditions. Higher MLP contents reduced the coefficient of friction, increased wear resistance, and promoted a transition from adhesive‐ to abrasion‐dominated wear under two‐body abrasion, while reducing plowing and micro‐cutting and promoting a more homogeneous distribution of embedded abrasive particles under three‐body abrasion. These results demonstrate the potential of compatibilized PP/MLP blends for upgrading MLP waste.