Lignin May be the Answer for Automotive Composites
If composite manufacturers and car makers had their way, carbon fiber materials would all but replace aluminum and steel in automotive manufacturing. It hasn’t happened to date because of the prohibitive expense of carbon fiber. Researchers at Washington State University aim to change that by adding lignin to the equation. If they succeed, they will turn both composites and automotive manufacturing on its head.
Lignin is an organic polymer that comes from certain kinds of algae and vascular plants. It is left behind when bio refineries convert natural materials into substances like ethanol or paper. Thus far, no one has found a viable purpose for lignin, so it is burned away by the same bio refineries that create it. Washington State University researchers believe they have a solution that kills two birds with one stone: harvest leftover lignin and combine it with carbon fiber to create a new composite material.
Lignin Alone Not Strong Enough
Researchers originally tried creating a new carbon fiber made with 100% lignin. As the thinking goes, lignin is both a natural and renewable material that could eventually be a replacement for standard carbon fiber materials made from polyacrylonitrile (PAN), a nonrenewable polymer.
They were successful enough at converting the lignin to a carbon fiber. But when they tested the resulting material for its tensile strength, they found it too weak for automotive applications. So they set about combining lignin and PAN in different ratios and measuring the results. They came up with something they believe is workable.
The ratio of lignin to the overall composition of the finished product ranged from 0% to 50% in the lab. Data showed that a hybrid material consisting of between 20% and 30% lignin is just as strong as 100% PAN alone. Moreover, they came up with a melt spinning process to combine the two substances into a single, strong fiber.
The next step for the researchers is to take their hybrid product into a manufacturing facility and test it under real-world conditions. This would be the big test. We already know that straight PAN is only about 25% as strong in the real world as compared to theoretical applications., so lab results do not mean a lot for the lignin-PAN composite. It has to be subject to real-world conditions before researchers can know just how strong it really is.
If They Succeed
Let’s say for the sake of this discussion that real-world testing proves the lignin-PAN hybrid worthy of automotive use. What would that mean to car makers? It would be a tremendous boon according to Rock West composites, a Salt Lake City, Utah company that deals in carbon fiber tubing, prepregs, and other composite materials.
Rock West explains that price is the prohibitive factor preventing auto makers from fully embracing carbon fiber right now. A lignin-PAN hybrid would theoretically be less expensive if, for no other reason, that it reduces the amount of PAN needed to create composite panels and components. The cost of PAN itself is the single most expensive component in carbon fiber manufacturing and fabrication.
In addition, a lignin-PAN hybrid would theoretically make carbon fiber manufacturing and fabricating more environmentally friendly. That says nothing about finally being able to use lignin for something productive rather than simply burning it off in bio refineries.
One of the goals of the Washington State University researchers was to make bio refineries more efficient and economically viable by eliminating as much waste as possible. Salvaging lignin and selling it to carbon fiber manufacturers would be a big step in that direction.
Sources:
Infosurhoy – http://www.infosurhoy.com/cocoon/saii/xhtml/en_GB/science/researchers-use-lignin-to-create-carbon-fiber-for-cars-and-planes/
