I thought this week I would go back to some natural (that is, plant-based) resins that are making some news and some headway in the industry. I keep writing about these things because plant-based or biocomposites are fast becoming mainstream and eventually, hopefully, will overtake the petroleum based resins and fibers. And, while a lot of the work that is being done is happening at places like MIT and Cal Tech, quite a bit of development work is also being undertaken by the major manufacturers of both resins and fibers.
On the research side is this new plant-derived composite based on nanocellulose that is apparently as tough as bone and as hard as aluminum. Researchers at MIT have been able to extract cellulose nanocrystals from cellulose fibers – that is, plant fibers – and bind them with a synthetic polymer (also plant based) in a 60% to 90% nanocrystal matrix. So, this material is a true composite in every sense of the word. What the MIT researchers said is that they “basically deconstructed wood and reconstructed it” to make a stiffer and stronger material than the original wood. And it can be 3D printed and machined as well. The pic above is of a 3D printed tooth cap that they made with this stuff that the machined into the shape that they wanted.
At the other end of the spectrum is an investment that Toray made in a Thai subsidiary to increase the production of cellulosic sugars that are the precursors to plant based fibers and resins. Toray has been working in this space industrially now for a number of years because they want to stay at the leading edge of the new “greener” developments in composites.
Cellulosic Biomass Technology Co. Ltd. (CBT, Bangkok, Thailand) cellulosic sugar production facility (bottom) and process (top)
Apparently CBT was established in Bangkok with Mitsui Sugar Co. Ltd. in 2017 to demonstrate their process. The photo above was taken in August of this year and shows that the plant is in production and making precursors for use by Toray for fibers, resins, and films for the composites industry. Toray has set a goal of using recycled resources like this wood waste based product to account for as much as 20% of their raw material stock for making fibers and resins. This plant uses what is left over from sugar cane and casava pulp that would otherwise have gone to a landfill or have been composted. These two traditionally unused waste streams can be converted into usable precursors for not only new fibers, but also polyphenol which is one of the primary precursors to composite resins.
In another example, there is ongoing work at NREL (National Renewable Energy Laboratory) in Colorado to develop plant-based epoxies that are easily recyclable at room temperature yet still have the strength and stiffness of traditional Bisphenol-A based epoxies. These resins are again derived from sugars or polysaccharides that can be produced from waste biomass. It is actually this NREL lab that developed the original low cost, bio-based acrylonitrile as a precursor backbone for traditional carbon fiber.
Now with their re-engineering of epoxies to have them derived from plant based sugars from waste biomass, and also have them inherently recyclable. The NREL researchers developed a special catalyst that works at room temperature to de-polymerize the plant-based epoxy into its original resin form. And, they have been able to use the recovered carbon fiber at least three times at full strength and stiffness in new composites.
That’s about enough for this week. I wanted to let everyone know again that I will 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, finally, for those of you that have not heard, 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, for those of you just tuning in. I got both the front and the back this time.
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