Conductive Lightweight Hybrid Polymer Composites from Recycled Carbon Fibers

The rapidly growing need of carbon fiber reinforced composites 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. The production of virgin carbon fiber is energy-intensive and costly. Recycling of carbon fiber reinforced composites can not only mitigate waste production and environmental pollution but also provide substantial economic benefits. However, recycled carbon fibers are generally produced in semi-continuous, chopped, or milled formats with inferior mechanical properties (18%−50% reduction in tensile strength). In this work, we will develop conductive lightweight hybrid polymer composites from low value recycled chopped/milled carbon fibers and graphene nanofillers through synergistic modification of carbon fibers, graphene sheets, and polymer matrix. The combined use of micro and nano fillers 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. In phase I, we will (1) Develop graphene-vitrimer nanocomposites with well dispersed graphene sheets as an advanced matrix to improve the reinforcement effect and conductivity of the composites; (2) Demonstrate the feasibility of fabricating high-performance conductive hybrid composites through rapid compression molding of graphene-vitrimer matrix with recycled carbon fibers. Tensile modulus of 50 GPa, flexural modulus of 40 GPa, and electrical conductivity of 103 -104 S/m are targeted (3) Investigate the reprocessibility, repairability, and recyclability of such composites. The upcycling of recycled carbon fibers into high- strength light-weight conductive composites can extract the greatest value from carbon fiber reinforced composite waste stream while significantly reducing the waste accumulation in the environment and increasing chemical circularity. The proposed composites with a combination of strength and conductivity would have great commercial potential in automobile, aerospace, and electronic device industry for applications in thermal and electrostatic charge management. In Phase II and Phase III, we will seek large scale production of such composites from low value recycled carbon fibers. We will partner with established companies in auto-industry and wind turbine manufacturing to carry out our commercialization plan.