Recycling of inside upholstery of end-of-life cars

A sustainable approach toward mechanical recycling unsortable post-consumer WEEE: Reactive and non-reactive compatibilization

While near-infrared (NIR) spectroscopy in post-consumer waste electrical and electronic equipment (WEEE) recycling accurately separates white or clear polymers, 40% containing dark plastics, termed 'unsortable WEEE,' are excluded from sorting lines and therefore incinerated or landfilled, causing environmental concerns. This study investigates the potential of using non-reactive and reactive copolymers as compatibilizers to enhance the performance of unsortable WEEE plastics free of brominated flame retardants. To the best of our knowledge, this is the first time that such copolymers have been explored as a solution for improving the compatibility of unsortable WEEE polymer blends. Initial trials with 4% of styrene-ethylene-butylene-styrene copolymer (SEBS-13) and SEBS-30-g-(maleic anhydride) copolymer (SEBS-30-g-MA MA) as compatibilizers showed insufficient results compared to virgin commercial polymers. However, the addition of higher concentrations of compatibilizers (i.e. up to 20 wt%) and the use of a SEBS having a higher styrene content (i.e. SEBS-30) improved the mechanical properties of the material, causing it to transition from brittle to ductile. This behavior was found more pronounced for the 20% non-reactive SEBS-30, for which the SEM analysis showed reduced phase segregation and revealed a more homogeneous fracture surface. This was further supported by Differential Scanning Calorimetry (DSC) analysis, which showed evidence of an interaction between one or more polymer phases. With a room temperature performance equivalent to that of virgin conventional polymers, the SEBS-30 compatibilization approach has made it possible to consider using unsortable WEEE streams as recycled materials in commercial applications.

The Effect of Different Compatibilizers on the Properties of a Post-Industrial PC/PET Blend

The substitution of virgin resins by recycled ones is a worldwide tendency that is supported by the fluctuation of oil prices and the transition to a circular economy. Polymeric blends have been intensively studied because of their ability to provide tailored properties for particular applications. However, in their design phases, the issue of end-life re-use had not been well addressed, and now difficulties in their recycling are arising. In this study, we investigated the effect of three different compatibilizers: two chain extenders (CEs), (1) a styrene-acrylic oligomer (ESAo), and (2) methylene diphenyl diisocyanate (MDI) and an impact strength modifier, (3) an ethylene copolymer (EMAco), for the recycle of a post-industrial polycarbonate/polyethylene terephthalate (PC/PET) blend. The materials were prepared by reactive extrusion and characterized by intrinsic viscosity (IV) measurements, mechanical tests, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy analysis (FTIR), and transmission electron microscopy (TEM). The introduction of each additive has been demonstrated to improve the compatibility between PET and PC in the post-industrial blend, leading to enhanced mechanical properties. The IV measurements increased to values that were comparable to the virgin material. In addition, CEs affected the crystallization of PET (as they reduced the degree of crystallinity), while EMAco acted as a nucleating agent. Morphological analysis enabled confirming the compatibilization effects induced by the tested additives.