Conductive Lightweight Hybrid Polymer Composites from Recycled Carbon Fibers

The rapidly growing need for carbon fiber reinforced polymers in various industry sectors, such as aerospace, automobile, and wind turbine poses exigent challenges for effective waste management and recycling protocols for their sustainable development. Since the production of virgin carbon fiber is energy-intensive and costly, recycling carbon fiber reinforced composites can not only mitigate waste production and environmental pollution but also provide substantial economic benefits. How the problem being addressed In this work, we will develop conductive lightweight hybrid polymer composites from low-value recycled milled carbon fibers and graphene nanofillers through synergistic modification of carbon fibers, graphene sheets, and vitrimer matrix. The combined use of micro and nanofillers can counterbalance the disadvantages of individual reinforcing fillers and synergistically improve mechanical strength and thermal/electrical conductivity of the materials. Polymer matrix crosslinked by dynamic covalent bonds (vitrimers) will be used to obtain by-design reproccessible and recyclable composite materials, achieving upcycling of recycled carbon fibers to green and sustainable multi-functional composites. What was done in Phase I We have successfully developed recyclable nano- and micro-filler reinforced vitrimer composites using recycled milled carbon fibers (NMVC-R2) with Young’s modulus of up to 15 GPa, and conductivity up to 2630 s/m, both of which represent the highest reported for milled carbon fiber composites. We also demonstrated the excellent repairability and closed-loop recyclability of NMVC-R2. What is planned for the Phase II project We will investigate various methods to enhance the mechanical properties, flame retardancy, and electromagnetic shielding effectiveness of NMVC-R2, scale up the fabrication method and produce samples for potential customers. Commercial applications and other benefits The upcycling of recycled carbon fibers into multifunctional light-weight composites can extract the greatest value from carbon fiber reinforced polymer waste stream while significantly reducing the waste accumulation in the environment and increasing chemical circularity. Furthermore, the closed-loop recyclability of NMVC-R2 would greatly improve the cost and environmental footprint of these materials, making lightweighting strategy more affordable. Given the lightweight, electric conductivity, and electromagnetic shielding effectiveness, the NMVC-R2 composites would have great commercial potential in the automobile, aerospace, and electronic device industries.