Feedstock agnostic upcycling of industrial mixed plastic from shredder residue pragmatically through a composite approach

Abstract

Shredding of a vehicle or an electrical and electronic equipment at its end-of-life (EOL) is a common practice to extract valuable critical raw materials. Unfortunately, this has the unintended consequence of mixing different polymers together and the only EOL options for this industrial mixed plastic waste are landfilling and incineration. Here in this work, we show that low value and highly heterogenous industrial mixed plastic can be mechanically upcycled sustainably using a composite approach, i.e., reinforcing with carbon fibres (CFs), glass fibres (GFs) and wood flour (WF). It was found that industrial mixed plastic can be successfully reprocessed, albeit possessing significantly poorer mechanical properties compared to its virgin counterpart. Nevertheless, the mechanical properties of the reinforced industrial mixed plastics were observed to be governed by the fibre or filler reinforcement, instead of the more inferior brittle industrial mixed plastic matrix. A lifecycle analysis (LCA) model with a functional unit designed using finite element analysis was developed to determine the environmental impact of upcycling industrial mixed plastic from shredder residue using this composite approach. In a “business as usual” scenario, our LCA model estimated a global warming potential (GWP) of 23 kg CO₂-eq. per f.u. and a net abiotic depletion potential of fossil (ADPf) of 431 MJ f.u.⁻¹. Using our proposed feedstock agnostic and pragmatic solution, the GWP and net ADPf could be reduced to only 11 kg CO₂-eq. per f.u. and 160 MJ f.u.⁻¹, respectively, when 40 wt% WF reinforcing filler was used. Our work also reports the influence of reinforcement on the tensile, flexural and fracture toughness properties, as well as the LCA hot spots in such an upcycling approach.