Rotational molding of polylactide (PLA) composites filled with copper slag as a waste filler from metallurgical industry

Abstract

The research work carried out so far indicates the ever wider possibilities and demand for shaping composite products in the rotational molding technology. This trend was the main reason to use waste-based filler from the metallurgical process as a filler for manufacturing polylactide (PLA)-based remolded composites. Copper slag (CS) was introduced in the single-step processing method to PLA matrix at 5, 10, 20, and 35 wt%. The rotomolded composites with different filler content were subjected to in-depth structural analysis discussed in relationship with mechanical and thermomechanical properties changes. Evaluation of the composite structures by scanning electron microscopy (SEM) and 3D computed tomography (3D CT) analyses showed that incorporating up to 10 wt% of the filler did not cause adverse changes in the filler dispersion in the product volume, which was homogeneous. Lack of unfavorable structural changes in composites with concentrations of up to 20 wt% was related to the rheological properties of the composition. Except for series with the highest filler content (35 wt%), the produced composites were characterized by increased stiffness and hardness than rotomolded parts made from pure PLA. Despite the deterioration of the tensile strength of composite materials using higher filler concentrations, the mechanical performance of 5 and 10 wt% showed an acceptable level while increasing the stiffness by about 15% compared to neat PLA. Moreover, it was shown that the interfacial adhesion between PLA and CS, despite the lack of surface modification of the filler waste, was advantageous.