Carbon fiber with a tensile strength of up to 2.45 gigapascals has been spun from two cheap leftovers, a tree-derived binder from paper production and the watery fraction of bio-oil from biomass pyrolysis. Engineers at Iowa State University say the material clears the strength and stiffness levels the U.S. Department of Energy recommends for automobiles, and they put its cost in the range of $5 to $7 a pound. That price would sit far below the petroleum-based carbon fiber now reserved for aircraft, race cars and high-end bicycles.
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Xianglan Bai, a professor of mechanical engineering and associate director of the university’s Bioeconomy Institute, leads the work. “This is where chemistry and materials science beautifully meet,” she said in the university’s announcement.
Kraft lignin and bio-oil as the precursor
Carbon fiber is made by heating a spun precursor fiber until little but carbon remains, and the precursor is the expensive part. According to the Iowa State announcement, petroleum-based precursors raise costs and confine the product to premium uses. Bai’s group instead starts with lignin, the binder in wood, taken as a byproduct of softwood kraft paper production, and pairs it with the aqueous bio-oil fraction that fast pyrolysis yields from materials such as corn stalks and wood chips. Biochar emerges from the same process.
Lignin has tempted fiber makers for decades. Japanese researchers studied it for carbon fiber in the 1960s, but the result performed worse than the petroleum-based version. Bai’s group has pursued biobased carbon fiber since 2015, supported by grants from the U.S. Department of Agriculture and yielding several patented and patent-pending technologies. Bio-oil plays a specific role: it modifies lignin that does not soften on its own into a precursor that can be melt-spun, and it cut the stabilization step from tens of hours to two to four hours.
Bai described the raw materials in plain terms, calling lignin a low-value byproduct of the paper and pulp industry and pairing it with aqueous bio-oil to produce a high-performance product. Industry partners include Harper International of New York, Latis Materials of Maine and Rise Energy, an Ames-based startup that supplies the bio-oil. Tannon Daugaard and Ryan Smith, both from the Bioeconomy Institute, are co-founders of Rise Energy.
Thermo-mechanochemistry and the 2.45 GPa result
The key process is what the group calls thermo-mechanochemistry: heating the lignin fiber while placing it under increasing mechanical stress. A 2024 paper in the Royal Society of Chemistry’s Green Chemistry series reported that applying heat and tension during stabilization and carbonization changes lignin’s chemistry, producing an oriented structure that graphitizes at low temperatures without chemical pretreatment or additives. Fibers from three lignin precursors reached tensile strengths of about 2.11 to 2.45 GPa and moduli of about 215 to 236 GPa after carbonization at only 700 degrees Celsius.
The new results use the same strength ceiling. The announcement reports tensile strength up to 2.45 GPa and stiffness up to 236 GPa, set against Department of Energy recommendations for the auto industry of 1.72 for strength and 172 for modulus. A 2025 conference abstract from Bai and presenter Abdulrahman Mohammed, listed in the AIChE annual meeting proceedings, describes bio-oil-modified softwood kraft lignin reaching 2.08 GPa strength and 197 GPa modulus and being tested as short fibers in epoxy composites.
The cost claim and the road to production
The price is where careful reading matters. One passage of the announcement says the process delivers much stronger carbon fiber “while maintaining costs below $5 per pound,” while another describes keeping costs “from $5 to $7 per pound.” The announcement does not say whether either figure is an estimate or what production scale it assumes, and the 2024 paper describes only a preliminary techno-economic analysis suggesting low production costs. For that reason the $5 to $7 range is the safer reading, with the lower figure best treated as an aspiration.
Scaling is the next hurdle. The work is still moving from batch production in the lab to continuous production, and the National Science Foundation is backing that step through its Translation to Practice program with a four-year, $2 million grant, award number 2612989. The project summary says commercializing the technology could significantly reduce manufacturing costs.
The idea has a track record of promises. In 2019 the company Attis Industries announced a funded research program with Iowa State to develop lignin-based carbon fiber, claiming its lignin could cut precursor costs to a fraction of the petroleum-based alternative. Those were company estimates, not independent verification, and seven years later the economics are still being worked out. If continuous production confirms even the upper end of the range, paper mills and bio-oil producers would gain a higher-value outlet for their byproducts, and automakers would gain a domestic source of strong, lightweight material.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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