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.

Study of the addition of monoalkylphosphonic acids onto trialkyl-substituted epoxides.

The addition of 2-chloroethylphosphonic acid (or ethephon), a well-known stimulating molecule for the production of latex by Hevea brasiliensis, onto 2,3-epoxy-2-methylbutane was investigated to enhance the understandings on the addition mechanisms of reagents of alkylphosphonic acid type onto trialkyl-substituted epoxides. It was demonstrated that the addition occurs according to a three-step mechanism including a rapid nucleophilic attack of the phosphorated anion on the most alkyl-substituted carbon of the oxirane, followed by formation of a dioxaphospholane structure with release of water, and finally a hydrolytic cleavage of the dioxaphospholane cycle to generate the regioisomer 1:1 adduct where the phosphorated group is on the less alkyl-substituted carbon of the initial oxirane.