In Brief
- WashU engineers developed new design principles for carbon fiber manufacturing.
- The process makes use of waste material, greatly reducing the costs of production and carbon emissions.
- This research has potential to improve the performance of carbon fiber in the aerospace, energy and automobile industries.
Carbon fiber is a key component in automobile manufacturing, aerospace engineering and energy infrastructure, but it mostly relies on petroleum-derived products, which can be expensive and contribute to carbon emissions. But what if carbon fiber was made of a free waste material and was as strong as - or even stronger than - the petrochemical-based products? Engineers at Washington University in St. Louis are unveiling that prospect in research recently published in the journal Matter.
"For the first time, this allows us to create renewable carbon fiber that reaches the high standard of quality used in automobile manufacturing," said Joshua Yuan, the Lucy & Stanley Lopata Professor and chair of energy, environmental and chemical engineering at WashU McKelvey Engineering. Yuan is also the director of the National Science Foundation (NSF) Carbon Utilization Redesign for Biomanufacturing (CURB) Engineering Research Center at WashU.
Key to the work is making use of a waste material called lignin, the second-most abundant natural biopolymer on earth. Lignin is produced as a byproduct of the paper pulping and biorefining industries, and ordinary disposal methods for lignin result in a substantial environmental footprint.
WashU engineers wanted to see if they could use lignin to improve production methods for carbon fiber. This human-made material is traditionally manufactured using synthetic polyacrylonitrile (PAN), a petroleum-derived product that is is mixed with chemicals, spun through tiny jets into fibers, washed and stretched. This type of production process for carbon fiber is called "wet spinning." However, PAN is not cheap, accounting for up to 50% of the total manufacturing cost of carbon fibers, which limits its use to high-end products, Yuan noted.
By adding affordable and abundant lignin to the process, the WashU team found that they could cut the use of PAN by half, reduce production costs by 25% and cut carbon emissions substantially. But the new carbon-fiber product they created still needed to meet automobile industry standards for tensile strength and elastic modulus.
So the researchers also developed another new process that greatly improves performance. That process involves deploying single-walled carbon nanotubes into the polymer matrix, acting almost like rebar in lining up the crystallization chemistry. This innovation revealed a new design principle for carbon material development.
"Crystallization alignment is critical for carbon fiber quality," Yuan said.
The carbon nanotubes allowed the researchers to make a precursor solution of the lignin and PAN. That solution was then extruded as fiber for the wet spinning process of production, then further heat-treated to strengthen the product.
Weiwei Li, a postdoctoral scholar in Yuan's lab and first author of the research, described their research as an innovation in three steps.
The first step was to create that nanotube template that can mix well with lignin and PAN and allows for high crystallization or orientation, Li said. Step two involves running that precursor solution through a wet spinning and tension-assisted heat treatment. Finally, one round of optimized carbonization fully strengthens the fiber. The three steps together maximized the crystallite content, while the carbon nanotubes guide the crystallite orientation to create rebar effects for outstanding mechanical properties.
"All these together allow us to create lignin-based renewable carbon fiber that has highly aligned crystalline structure," Yuan said.
The automobile industry is just the entry point for markets of optimized carbon fiber; it's used in many industries, from sports equipment to wind turbines.
"Carbon fiber reinforces plastics and has very broad application," Yuan said.
Li W, Hu C, Zhu T, Chen Y, Zhang R, Jiang P, Dhatt PS, Li J, Xiang S, Liu M, Fei CJ, Liu J, Dai SY, Yuan JS. Transforming renewable carbon fiber performance, economics, and sustainability via oriented crystallization design, Matter, 2026, 103001. DOI: https://doi.org/10.1016/j.matt.2026.103001
This research received support from the Lucy & Stanley Lopata Professorship and US Department of Energy Projects DE EE 0008250. Further support came from the Institute for Materials Science and Engineering (IMSE) and Chemical and Environmental Analysis Facility (CEAF) at WashU as well as the NSF CURB Engineering Research Center (NSF EEC 2330245).
