This week I’m going to go back to being a bit technical and talk about a completely sustainable material that is being researched and developed as a sustainable precursor for the string (fiber) part of a composite - Nanocellulose. Primarily this is for carbon fiber, but it can also be used as the backbone or additive in the precursor for other organic fibers. Nanocellulose is exactly what you might think it is, it is the cellulosic (fibrous) part of wood. If you remember, I have talked quite a bit about how Mother Nature figured out composite materials long before man even existed. Trees make the strings and glues of wood using long chain sugars, cellulose (strings), lignin (glues), and pitch (yes – tree sap).
Nanocellulose itself consists of very short crystalline fibers of cellulose. These are the building blocks of the structure of all plants where the plant makes these very short (a few micrometers) crystalline “fibrils” and glues them together with lignin and often pitch to make a wood fiber. This stuff is 10 times stronger than steel and yet weighs 5 times less. It has the stiffness of Kevlar® fiber, and is nearly completely transparent.
The four pictures above are from Wikipedia, but they represent several different things. The upper left is a mass of nanocellulose fibrils all put together in a semi-ordered or semi-crystalline fashion. The one on the top right is a micrograph of nanocellulose fibers adsorbed onto a silica surface. And the bottom two pics are to the left a solar cell on a flexible nanocellulose film and to the right nanocellulose crystals self-organized into a bio-iridescent set of sequins. So, even though these things all look very different, they are all made out of the same stuff.
So, what is coming in the future for this stuff? There are a number of companies and countries that are pursuing the development of composite fibers, carbon fiber precursors, and carbon fiber additives to enhance strength or toughness or stiffness of the fiber. And since these fibers are inherently biodegradable and reusable – you just take them apart down to the nanocellulose fibrils – they are one of the starting points for a new generation of sustainable composites.
Nanocellulose is also making its way into the resin systems that are being developed for composites. I have talked quite a bit about the resin business and why the formulas for making resins are so closely held by the companies that make them. It is primarily due to the additives that are added to a basic bis-phenol A based epoxy resin that make each manufacturer’s resin just a little different and tailored to a particular application. So, now, since nanocellulose is nearing industrial production, and since it has these wonderful mechanical and physical properties, several resin manufacturers are tinkering with this stuff to see what they can come up with to enhance their resin systems. Look for some new “improved” resins that outperform what is commercially available today – especially for some high end applications – to hit the market within the next couple of years. In other words, the race is on now that researchers have been able to extract and purify this stuff directly from wood waste.
Stay tuned here and we will get back to this in a future post. But now it is time to remind everyone that I will be giving a short talk and doing a book signing at the Bay Area Maker Faire on Mare Island this weekend. I will be at the Faire all weekend, but my talk is on Sunday, Oct. 15 at 1 PM and I will be signing books right after that talk. I think next week my post is going to be about that experience, and I will include the PowerPoint deck that I am going to use to give the talk. Hopefully the folks putting on the Faire will record it so that anyone that signs up on Make: and joins the movement will be able to see it.
That’s about enough for this week. I am going to be reminding everyone right here each week that I will also be presenting two papers toward the end of this year. Both of them are about sustainability of composites – a subject that all of you that have read my posts know is a passion of mine. The first one is a paper about sustainability efforts for composites in general, with a focus on what to do with wind turbine blades. That one is going to be at the International Mechanical Engineering Congress and Exhibition in New Orleans October 29 to November 2 (https://event.asme.org/IMECE). The second one will be at the Carbon Fiber Conference in Salt Lake City being put on by Composites World (https://www.carbonfiberevent.com/). In that presentation I will focus on current work in sustainability of carbon fiber in particular. I’m of course going to talk about new fibers and fiber precursors made from plants, so again, focusing on closing the circle. And I’m also on a panel discussion about the Titan disaster at the Carbon Fiber Conference, so that may end up being a somewhat lively discussion.
And, finally, as another reminder, my book has been published and is for sale. 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, except that I charge $8 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’s a picture of the book cover, for those of you just tuning in.
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