Carbon fiber

Carbon fiber is essentially long chains of graphite polymers. They have high tensile strength compared to their weight and are very heat resistant. Carbon fibers can be woven into a very strong fabric and if paired with a resin can retain a shape making strong, light parts.

Commercial Production

Carbon fiber is normally produced by repeatedly heating Polyacrylonitrile (referred to as PAN, (C3 H3 N)n.) in an anaerobic (no oxygen) environment. PAN is a precusor polymer to a number of other products one of which is ABS. (1, 2

The first heating cycle apparently causes a strands of PAN to form cycles bonding the nitrogen to the adjacent carbon. The second heating cycle at around 700C causes the hydrogen to off-gas causing the chain to become aromatic (very stable chemically bonded rings). The third heating at 400-600C causes two of these aromatic chains to merge into a graphite ribbon structure, off-gassing more hydrogen. The fourth at 600-1300C merges two of these graphite ribbon structures causing half the nitrogen to off-gass and producing a mostly carbon based ribbon. (3 4) Presumably subsequent heatings will make this ribbon wider and wider resulting in larger sheets and less nitrogen content.

Reference #4 seems to indicate that the commercial process is actually more complicated. I'm not sure if just the heating process is enough and the rest of the process is to produce a higher quality product or if the whole process is needed. So more research is needed.

Alternate Production

Cellulose ((C6 H10 O5)n) is slightly similar to PAN (C3 H3 N)n.) the differences being: Cellulose's chain structure is not nearly as simple as PAN's, Cellulose contains oxygen instead of nitrogen, and Cellulose has a bit more of a hydrogen to carbon ratio. However I'm curious if a similar heating process could produce a similar result.

Cellulose fibers can be fairly easily obtained in a number of ways, the one that stands out to me is using a costic soda solution to soak bamboo, which causes the cellulose fibers to easily separate. You can use the fibers for other things like clothing, but might also use it in the above process to turn into carbon fiber. You can also get long strands from things like hemp of just traditional flax.

Follow up

Found this related article, seems like they are going about it a different way but did not get far in reading it. https://chemistry-europe.onlinelibrary.wiley.com/doi/full/10.1002/open.201800180

Notes from JJ

Okay, so the reason that PAN is used and heated to make carbon fiber is because it's already in that position to where if you heated it up, it sticks together.

You'd need to find some way to change cellulose into something that would give you an end product of (some technical term I forgot) a sheet of a bunch of planar sp2 carbons. If you just directly heat up cellulose, you're not going to get that. I think the first thing that would happen is that the beta 1,4 glycosidic linkages would break down, so you'd just end up with a bunch of smaller sugars. So you might make syrup, not carbon fiber. But maybe if you torched it even more, it would turn into carbon... I'm not entirely sure of how the chemistry of that would work out off the top of my head. But at that point, I think you're just going to be turning it into carbon, and then finding some way to link it together in a vinyl polymer that would stick to itself like PAN does when heated, and then heating it. So PAN but with more steps.