Grant: Discovery Launch Supplement

Mechanical recycling of plastics, typically involving the reprocessing of plastic recyclates through extrusion, currently represents the most economically viable alternative to produce recycled plastics that can be cost competitive with virgin plastics. However, it faces significant challenges that limit its efficiency and rate. These challenges include the degradation of recycled plastic properties, the rejection of substantial portions of mixed plastic waste streams during sorting, inadequate reprocessing conditions, and limited understanding of how the properties of plastics evolve through repeated mechanical recycling. Presently, plastic recycling rates remain at a mere 9% both in Canada and worldwide. In parallel, incentives and governments strategies aim not only to increase recycling rates but also to implement closed-loop and extensive mechanical recycling. This broader goal entails addressing the aforementioned challenges to facilitate the recycling of complex mixed plastic waste streams and ensure that plastics can withstand repeated recycling without significant property deterioration. My long-term vision is to create a new class of performant yet recyclable plastic materials that contribute to the transition towards a circular economy. This research program will focus on the development of new approaches to improve the performance and compatibility of mixed plastic streams to enable their repeated mechanical recycling, by leveraging nanotechnology-based strategies and advanced extrusion techniques. To achieve this goal, this program is divided in 3 short-term objectives (STO). First, STO1 will investigate the potential of 2D NP as multifunctional additives for enhancing the compatibility and performance of immiscible plastic mixtures. STO2 will focus on the development of an innovative process based on sub-critical gas (SCG) assisted extrusion to improve mechanical recycling of 2D NP enhanced mixed plastics. Compared to typical extrusion process commonly used in mechanical recycling, the SCG assisted extrusion will be optimized to ensure: (1) better mixing of different phases in plastic mixtures, (2) better dispersion of 2D NP and consequently higher leverage of their role investigated in STO1 and (3) higher thermal stability during repeated recycling. STO3 will build on findings of STO1 and STO2 to investigate 2D NP enhanced plastic mixtures as a feedstock for material extrusion-based additive manufacturing (MatEx AM) and their closed-loop recycling through MatEx AM. The knowledge generated from this program will offer innovative solutions to bring complex mixed plastic waste streams that possess low intrinsic value from landfills or incineration to recycling and promote their repeated recycling. This program will train 8 HQP (2 PhD, 3 MASc, 3 UG) with fundamental knowledge on polymer science and multidisciplinary marketable skills in fields expected to see large growth such as polymer nanocomposites, plastics recycling and AM.