The lignin remaining after plants and trees are converted into paper, ethanol or other products is typically burned to produce steam at biorefineries or landfilled. Washington State University researchers have discovered a valuable use for these residues: lignin is transformed into carbon fiber to yield a strong, low-cost material for the manufacture of automotive or aircraft parts.

Using the low-value lignin reduces the cost to fabricate high-value products, as the carbon fiber currently used Carbon fiber car parts, such as this bumper, could someday be made from waste lignin. Source: fabiodevilla/Shutterstock.comCarbon fiber car parts, such as this bumper, could someday be made from waste lignin. Source: fabiodevilla/Shutterstock.comis derived from polyarylonitrile (PAN), a pricey, non-renewable polymer. The researchers developed a way to combine the high strength of PAN with the low cost of lignin to produce an automobile-grade carbon fiber.

The process entailed mixing lignin with PAN in amounts of 0 to 50 percent, after which the polymers were melded together into a single fiber by melt spinning. The resulting structural and mechanical properties were assessed by electron microscopy and other techniques, revealing that use of as much as 20-30 percent lignin does not undermine material strength.

The lignin carbon fibers might have automobile applications such as internal parts, castings and tire frames. The researchers will next take these fibers to an automobile manufacturing plant to test their strength in a real-world scenario.

The research was presented at the 254th American Chemical Society National Meeting & Exposition, August 20-24, 2017, in Washington, D.C.

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