Upgrading of Automotive Polymer Fractions Obtained by a Flotation Separation Process: Properties and Structure

This study investigated the upgrading process of polymer fractions obtained from automotive waste by a three-stage flotation-sedimentation separation process. The separated automotive recycled blend (ARB) fraction was modified with a compatibiliser at contents of 5, 10 and 15 wt%, and the resulting blends were processed by extrusion and injection moulding. Multipoint FTIR analysis confirmed the multicomponent character of the ARB fraction and indicated the presence of, among others, polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS), high-density polyethylene (HDPE) and polystyrene (PS). The influence of compatibiliser addition on density, Shore D hardness, tensile properties, thermal behaviour and fracture-surface morphology was evaluated using gas pycnometry, static tensile testing, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results showed that increasing compatibiliser content gradually reduced the density of the blends, while hardness remained at a level comparable to that of the reference material. Tensile testing indicated that the addition of the compatibiliser reduced Young's modulus, whereas ultimate tensile strength and tensile stress at break were maintained close to the unmodified blend. Among the modified blends, the most favourable balance of the evaluated properties was observed for the ARB/10C sample containing 10 wt% compatibiliser. This blend exhibited the highest tensile stress at break among the investigated blends and a comparatively compact fracture-surface morphology. DSC analysis showed similar principal thermal transition ranges for all blends. The results indicate that 10 wt% compatibiliser is an optimal addition for upgrading recycled automotive polymer fractions.