Fully Bio-Based Carbon Fiber Almost Ready to Come Out of the Lab
- Ned Patton
- Jun 10
- 6 min read
Last week I focused on the up and coming composite resins that are entirely plant based, mostly using lignin but also using plant oils. Mostly I focused on the ones that are ready for prime time and are seeing the potential for commercial viability at scale. So, this week I thought I would look at the other piece of the whole plant-based advanced composite business – plant-based carbon fiber and where we stand in development of something that has the potential to be made and sold on the scale needed to effectively replace PAN based carbon fiber.
I have written about the fibers in the pic above previously, so I thought I would start here and expand a bit on some of the newer stuff that is coming along, as well as bring back into focus some of the previous efforts that I have written about to see if there have been any movements toward commercialization.
The pic above is of the lignin based carbon fiber that was developed by the German Institutes of Textile and Fibre Research in Denkendorf (DITF in the original German). I wrote about these folks and their work developing a melt spun fiber that is nearly entirely lignin based. They had to add a little bit of cellulose to the mix at the time to keep the short chain lignin molecules from breaking apart during the melt spinning process, but they were able to successfully do this and create a lignin-based carbon fiber from forest products waste that has very nearly the same mechanical properties as common commercial carbon fiber (roughly a T-300 equivalent industrial grade carbon fiber).
There is of course also the plant-based carbon fiber that is being commercialized by Syensqo (formerly Cytec/Solvay) that was developed by Southern Research, the New Jersey Institute of Technology, and Trillium. This fiber is a traditional PAN based carbon fiber, but rather than using petroleum feedstocks, they used forest products and agricultural waste cellulose to break down into cellulosic sugars that they converted into Acrylonitrile to make PAN fibers. And of course these carbon fibers are indistinguishable from traditional carbon fibers because they use the same precursor.
I also found a newer (2022) article about a continuous process developed by the same German researchers as the Lignin based carbon fiber using what they call a “Stabilization and Carbonization” continuous process where they feed in cellulose fibers and feed out carbon fibers with mechanical properties very similar to PAN based carbon fiber.
This process appears very much like the traditional PAN fiber process, except that used a little bit different and simpler air gap spinning process to make the fibers before their “stabilization” and traditional carbonization (pyrolysis) processes. The stabilization step appears to be similar to the initial preparation of most fiber precursors where a lot of the water and some other short chain hydrocarbons are driven off before they are carbonized at something like 1400 degrees C in a nitrogen atmosphere to drive off everything that isn’t carbon. The fibers that they made rival the mechanical properties of traditional petroleum derived PAN-based carbon fiber. And they made these fibers from cellulose which, as I have written before, is the most abundant organic molecule on the planet.
It appears to me that this lab scale demonstration could very easily be scaled up to industrial production levels, and the cost of this fiber, since its precursors can be sourced from agricultural and forest products waste, could be significantly less than carbon fiber made using petroleum based precursors.
Another very interesting development cited in Nature Communications (https://www.nature.com/articles/s41467-022-33496-2) by a group of researchers at Donghua University in Shanghai, China, is the creation of carbon fibers made from lignin that are not the traditional melt or solution spun fibers, but instead are fibers assembled by carbon nanotubes that are created from the aromatic rings (6-sided carbon ring structures) that are abundant in lignin. Rather than focus on trying to make the bonded fiber structure of a traditional carbon fiber like those made from PAN, these researchers were able to reduce the lignin to carbon nanotubes and assemble them into a long fibers. They describe their process as preparation of these high performance fibers from lignin by “solvent dispersion, high temperature pyrolysis, catalytic synthesis, and assembly”. If you read down through this article, they exposed a solution of lignin in a solvent to a high temperature oven where the solvent evaporates very quickly, and the lignin is further decomposed into CO and hydrogen. Then this gas mixture is passed over a bed of iron particles that act as a catalyst to produce carbon nanotubes and water. The nanotubes are then assembled in a water bath into a “sock-like” integrated mass which is then pulled through a spinneret into fibers. These assembled fibers are then again pyrolyzed to drive off everything that isn’t carbon. And they did this in a continuous process.
While this may seem to be a fairly complex process, it struck me as potentially viable because quite a few petrochemical processes involve first breaking down the long chain hydrocarbons or reducing the carbon chains to smaller chains or even to CO (carbon monoxide) which will react with almost anything. So, this process seems like it is using lignin in a similar way to how a petrochemical plant uses crude oil to create the chemistry that is desired.
Finally, one more that I found is in Sustainable Chemistry and Engineering (https://pubs.acs.org/doi/10.1021/acssuschemeng.3c06954#) where another group of German researchers made carbon fibers using cellulose acetate rather than PAN, and used a very similar process to how PAN carbon fibers are made – melt spinning, deacetylation (like PAN conditioning), and pyrolysis to make a carbon fiber.
Note that the little flask next to the pile of cellulosic forest products waste that is going into their spinning process is acetic acid. That is what they dissolved the cellulose in to spin the fibers. Then they dried them out and put them through their pyrolysis oven portrayed by the cartoon barrel oven and produced their carbon fiber. This also looks like a scalable and continuous process that could be commercialized.
So, the bottom line with all of this is that there are lots of successful experiments that have been done that show that there are potentially scalable processes to make carbon fiber from cellulose derived from forest products and agricultural waste, and even some using lignin as well as some using lignin mixed with a little cellulose. All it is going to take is for more companies like Syensqo (Cytec/Solvay) to take a few of these processes out of the lab and into the carbon fiber plant. And from the looks of the results that are coming out of these studies, the carbon fiber produced using these processes will easily compete with the standard grades of carbon fiber that are made by the mile now using PAN fiber precursors.
That’s about it for this week. As always, I hope everyone that reads these posts enjoys them as much as I enjoy writing them. I will post this first on my website – www.nedpatton.com – and then on LinkedIn. And if anyone wants to provide comments to this, I welcome them with open arms. Comments, criticisms, etc. are all quite welcome. I really do want to engage in a conversation with all of you about composites because we can learn so much from each other as long as we share our own perspectives. And that is especially true of the companies and research institutions that I mention in these posts. The more we communicate the message the better we will be able to effect the changes in the industry that are needed.
My second book, which should be out in the fall, is a roadmap to a circular and sustainable business model for the industry which I hope that at least at some level the industry will follow. Only time will tell. Since my publisher and I have finally come to agreement about the title for my next book, our daughter has been kind enough to put together a draft of the cover of the book for them to use to come up with a final version. So, I’ve included the approved cover at the end of this post as promised. Let me know whether or not you like the cover. Hopefully people will like it enough and will be interested enough in composites sustainability that they will buy it. And of course I hope that they read it and get engaged. We need all the help we can get.
Last but not least, I still need to plug my first book, so here’s the plug. The book pretty much covers the watershed in composites, starting with a brief history of composites, then introducing the Periodic Table and why Carbon is such an important and interesting element. The book was published and made available last August and is available both on Amazon and from McFarland Books – my publisher. However, the best place to get one is to go to my website and buy one. I will send you a signed copy for the same price you would get charged on Amazon for an unsigned one, except that I have to charge for shipping. Anyway, here’s the link to get your signed copy: https://www.nedpatton.com/product-page/the-string-and-glue-of-our-world-signed-copy. And as usual, here are pictures of the covers of both books.
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