Closeup of microscopic “rebar” that adds strength to carbon fiber. This extra strength is incorporated into the material via functionalized single-walled carbon nanotubes. The manufacturing process was developed by WashU engineers to make use of waste material lignin and further strengthen carbon fiber used in automotive and energy industries.
Image Credit: Yuan lab
Scientific Frontline: Extended "At a Glance" Summary: Renewable Carbon Fiber Production
The Core Concept: A novel manufacturing method that produces high-quality, renewable carbon fiber by blending synthetic polyacrylonitrile (PAN) with lignin, an abundant natural waste biomaterial.
Key Distinction/Mechanism: Unlike traditional manufacturing that relies entirely on expensive, petroleum-derived PAN, this process incorporates single-walled carbon nanotubes into the polymer matrix. These nanotubes act as structural "rebar" to align the crystallization chemistry, maximizing the mechanical properties of the fiber.
Major Frameworks/Components:
- Lignin Integration: Utilizing lignin—the earth's second most abundant natural biomaterial and a byproduct of paper pulping and biorefining industries—to replace up to 50% of the synthetic PAN.
- Nanotube Templating: Deploying single-walled carbon nanotubes to create a highly oriented crystalline structure within the lignin-PAN precursor solution.
- Wet-Spinning and Heat Treatment: Extruding the precursor solution via a tension-assisted wet-spinning process, followed by an optimized carbonization phase to fully strengthen the resulting fiber.
Branch of Science: Materials Science, Chemical Engineering, and Environmental Engineering.
Future Application: Broad commercial integration in automobile manufacturing, aerospace engineering, sports equipment design, and energy infrastructure, such as wind turbines.
Why It Matters: This innovation reduces production costs by 25% and substantially lowers carbon emissions, all while maintaining the strict tensile strength and elastic modulus standards required for high-end industrial and automotive applications.
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. What if carbon fiber were made of a free waste material and could be as strong as, or even stronger than, petrochemical-based products? Engineers at Washington University in St. Louis are unveiling that prospect in research recently published in the journal Matter.
“This allows [us], for the first time, to create renewable carbon fiber that reaches the high standard of quality used in automobile manufacturing,” said Joshua Yuan, chair and Lucy & Stanley Lopata Professor in Energy, Environmental & Chemical Engineering, and director of the Carbon Utilization Redesign for Biomanufacturing (CURB) Engineering Research Center at the McKelvey School of Engineering.
Key to the work is making use of a waste material called lignin, the second most abundant natural product or biomaterial on Earth, which is a byproduct of the paper pulping and biorefining industries. Its disposal contributes to a substantial environmental footprint.
Carbon fiber is traditionally manufactured using synthetic polyacrylonitrile (PAN), a petroleum-derived product used in a wet-spinning industrial process. However, PAN is not cheap; it accounts for up to 50% of the total manufacturing cost of carbon fibers, which limits its use to only high-end products, noted Yuan.
With the addition of affordable and abundant lignin to the process, the team cut the use of PAN by half and was able to reduce production costs by 25% and carbon emissions substantially. However, the fiber still needs to meet automobile industry standards for tensile strength and elastic modulus. Consequently, the researchers developed a new manufacturing process that greatly improves the material's performance. This process involves deploying single-walled carbon nanotubes into the polymer matrix, where they act almost like rebar in aligning the crystallization chemistry. The innovative process 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 create a precursor solution of lignin and PAN. This solution was then extruded as a fiber during the wet-spinning production process, and then further heat-treated to strengthen the product.
Weiwei Li, a postdoctoral scholar in Yuan’s lab and the first author of the study, described the research as a three-step innovation.
The first step was to create a nanotube template that mixes well with lignin and PAN and allows for high crystallization, or orientation. The second step involves running the precursor solution through a wet-spinning process and tension-assisted heat treatment. Finally, one round of optimized carbonization is used to fully strengthen the fiber. The three steps synergistically maximize the mechanical properties of the resulting carbon fibers.
“All these together allow us to create a lignin-based renewable carbon fiber that has a highly aligned crystalline structure,” Yuan said.
The automobile industry is just the entry point for the optimized carbon fiber market. The material is used in many industries, from sports equipment to wind turbines.
“Carbon fiber reinforces plastics and has very broad applications,” Yuan said.
Funding: This research received support from the Lucy & Stanley Lopata Professorship and U.S. Department of Energy projects (DE-EE0008250). Further support came from the Institute of Materials Science & Engineering (IMSE) and the Chemical and Environmental Analysis Facility (CEAF) at Washington University in St. Louis, as well as the National Science Foundation CURB Engineering Research Center (NSF EEC-2330245).
Published in journal: Matter
Authors: Weiwei Li, Cheng Hu, Tianle Zhu, Yayun Chen, Rui Zhang, Ping Jiang, Puneet S. Dhatt, Jinghao Li, Sisi Xiang, Mengqiao Liu, Chengcheng J. Fei, Jenny Liu, Susie Y. Dai, and Joshua S. Yuan
Source/Credit: Washington University in St. Louis | Leah Shaffer
Edited by: Scientific Frontline
Reference Number: ms091826_01