This Nasty Oil Byproduct Could Be a Cheap Way to Make Carbon Fiber

One result of making gasoline might just be a way to build lightweight cars for a lot less money.

byMar 22, 2022 8:57 AM
This Nasty Oil Byproduct Could Be a Cheap Way to Make Carbon Fiber
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In a paper published by MIT, scientists have worked out a way to use a byproduct from refining oil to make fibers strong and fine enough to fashion into a new composite that can form parts of car bodywork. It's relatively cheap and simple to manufacture, meaning there's a chance we could use it to stop cars getting even heavier than they are now. Think of it as a carbon fiber-type material that's not reserved exclusively for high-end applications.

Of course, carbon fiber is good stuff if you want to make something lightweight and incredibly robust. There's a reason Formula 1 cars use so much of it and why it's the premium material for making hypercars, in attempt to seek that perfect ratio of horsepower-to-weight. But it's also really expensive, so not really practical to use for making mass production cars.

Fibers made from petroleum pitch, MIT/Nicola Ferralis

Because the fibers normally used to make the composite are made from polymers, the process of making carbon fiber is very costly. Regular carbon fiber takes refined, processed petroleum and then polymerizes it to get something like polyacrylonitrile to then make the fibers out of. That, according to the researchers, makes automotive-grade carbon fiber between $10 and $12 per pound—that's a heck of a lot more than steel (¢75/lb) or even aluminum ($2/lb) and Nicola Ferralis, one of the scientists working on the project, says making an average pickup truck would cost twice as much if you used carbon fiber instead of steel. 

It'd also make it way lighter and more efficient with fuel or battery power, though. So if there was a way to use low-cost materials to make effective carbon fiber, that'd be an important breakthrough in these increasingly fuel-starved times

Enter the hero of the hour: petroleum pitch. Literally the stuff left at the bottom of the barrel of oil, the stuff no one can think of anything else to do with. Described as "a hodgepodge of mixed heavy hydrocarbons," Ferralis called pitch "incredibly messy" and said “that’s actually what makes it beautiful in a way, because there’s so much chemistry that can be exploited. That makes it a fascinating material to start with.”

Pitch isn't expensive, either. It's "the heavy, gloppy waste material left over from the refining of petroleum, material that refineries today supply for low-value applications such as asphalt, or eventually treat as waste." So basically, oil companies want someone to take it off their hands. 

Turning this nasty hydrocarbon soup into something that makes very fine, consistent fibers turns out to be easier than anyone could've hoped—it's the same polymerization process but with a few controls switched to mean you can use something totally non-homogenous to make very regular, defined products with an expected elasticity and density. 

Asmita Jana, one of the researchers involved, said that they were able to compile graphs that could be shared with any companies wanting to use the technology so that they could easily predict what the end product from their pitch processing would be. “We were able to reproduce the results with such startling accuracy,” Jana explained. 

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