The short answer is yes, it is possible and it is even being done albeit not quite on the scale it needs to be done yet. One of my readers offered a great suggestion that he would like to hear a bit about polyester and the challenges and successes that researchers have had dealing with end of life glass fiber / polyester composites. I agree with him, so I decided that this week I would take a bit deeper dive into this very important and soon to become critical development. And I would like to thank him for a great idea. So, here's a challenge for the rest of you who read this blog - let me know what you want to hear about. I relish the opportunity to do some research and get all of you answers if I don't have them right on the tip of my tongue. We are all in this together at the end of the day - right?

What We’re Looking for When We Recycle the Polyester Resin From Fiberglass
I thought this was a nice pic to start off with in this story. While this is actually a pic of an inherently recyclable bio-based polyester resin that is the product of the EOCENE project in Spain, this is actually the ultimate goal in recycling of cured polyester resins from glass/polyester composites.
What I want to talk about in this post, however, is what do we do with used boat hulls and end of life turbine blades. There are mountains of this stuff piling up all over the world, and by and large they are glass fiber / polyester composites. Especially the boats and wind turbine blades that have reached the end of their lifespan. The boats were made more than 50 years ago in most cases and most of the newer resins and fibers hadn’t even been invented yet, or were prohibitively expensive for the amount of material that would go into the hull of a 36’ trawler. Wind turbine blades that have come to the end of their lives were made more than 20 years ago in most cases and even longer in some cases if they haven’t experienced too much fatigue damage during their lifetimes. They were made using fiberglass because carbon fiber was 10 times the cost per pound that it is today when they were built.

Historically, when fiberglass composites came to the end of their lifetimes, they had long been considered to have very little value. That is because the plastic resin – cured polyester – once it is cured and becomes solid is famously hard to take back apart. The resin itself, if it can be reclaimed in a liquid form, it inherently rather valuable. This is because when you are able to take the resin apart, you can create oily substances that contain most of the carbon from the original resin. That oily liquid is easier and less expensive to use than what it costs to refine petroleum into these same organic oils. And if the recycling process has high yield and isn’t expensive in its own right, these resins can be made into new polyester resins, or many other high value products at lower cost than getting them from petroleum. All of the refining was done when the resins were originally made, so this does make some sense.
This new polyester recycling technology, fortunately, is beginning to evolve rather rapidly. There are initiatives ongoing in Europe and the US to start recycling fiberglass and reclaiming both the glass fiber in chopped fiber form, and the polyester resins in liquid form, both of which can then be sold into either different sectors of the composites business, or in the case of the oil from the reclaimed resin can be used as less expensive feedstocks for some of the higher value organics, and even as feedstock to the pharmaceutical industry.
In Europe we have a few examples of this happening, starting with something that I have talked about previously, the 2015 and 2023 updates to the 2008 EU Waste Framework Directive banned the disposal of fiberglass boats in landfills, and stood up a cradle to grave responsibility framework that places the responsibility for disposal of used fiberglass boats into the hands of the boat manufacturers. The result of this is that there are several companies that have fairly recently been stood up in the EU to recycle old fiberglass boats and wind turbine blades. Only two companies that I have been able to find, however, actively recover the polyester resin from these used up fiberglass structures. Both of them end up with an oily substance that can be reused to make new resin or be used as feedstocks for other organic products.
Composites Recycling, which I have talked about quite a bit in this space, is of course the largest of these organizations in the EU, and arguably has the most commercially viable and scaled up approach to recovering the resin from end-of-life polyester based fiberglass composites. Their approach is to use a lower temperature pyrolysis-like process, meaning that the fiberglass scrap is heated in either an inert atmosphere or in a vacuum to a temperature where the cross-linked bonds in the cured polyester resin that binds the fibers together are broken by the heat. What results is an oily substance that they call “pyrolysis oil”. This oily stuff is apparently ready to use almost directly either in a new resin or even in other petrochemical products.
The other company in the EU, Korec of Italy, uses a little different twist on this same process. They introduce CO2 into their low temperature pyrolysis process, and are able to perform this feat at lower temperatures than what Composites Recycling is using. They do end up with a very light coating of a char-like substance on the fibers, but that is apparently fairly easily removed from the fibers. And what results is a fairly clean resin that is ready to be reused. The pic below is from an article I found about them. This oily product of their CO2 thermolysis process looks to be fairly clean. Korec of course is not as far along on this path as Composites Recycling, but at least there are two organizations in the EU that are able to recover useful product from the polyester resins in used up boats.

Recovered Oil by CO2 Thermolysis by the Korec Process.
Here in the US, there have been research papers and programs at DOE’s Office of Scientific and Technical Information (OSTI) that have demonstrated at the lab scale the ability to use a solvolysis process to reclaim the organics from polyester resins. These studies have used a couple of techniques, mostly using high temperature and pressure water. Supercritical water (3200 psi and a bit more than 700 degrees F) will break up the cross-linked bonds in polyesters. If something like methanol or acetone is added to the water, this happens at a much lower temperature and pressure than what is required to have water go supercritical.
There is one company, Eastman Chemical Company, that has what they call “molecular” recycling of polyester resins. They have a new facility in Kingsport, Tennessee entirely devoted to the recycling of used polyester. Their process, which they call Polyester Renewal Technology, uses methanolysis to break apart the cross-linked bonds in polyester resins. Methanolysis is another solvolysis technique that does not necessarily involve water, but it does involve methanol at high temperatures and pressures to break down the polyester cross-links. And they claim that their process reclaims almost all of the original polyester resin in the same liquid form that it was when it was cured, so it can be used over and over again. Pretty slick process.
A little history about Eastman Chemical. For those of you that remember the Simon and Garfunkel song “Kodachrome” this is the same Eastman Kodak company that created Kodak photographic films. George Eastman created Kodak to provide a reliable supply of chemicals for its Kodak film business. Kodachrome was Kodak’s original color photographic film, and it was in nearly every film camera from 1935 until the advent of digital photography. I know I must have bought at least 100 rolls of the stuff to feed my 35 mm SLR cameras. And anyone that doesn’t know what that is, please just ask me. I was a bit of a photo buff as a youngster.
That’s about it for this week. I hope everyone that reads these posts enjoys them as much as I enjoy writing them. As usual I will post this first on my website – www.nedpatton.com – as well as 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.
I also wanted to let everyone know, again, that I have finished the first draft of my second book. This one is about what I have been writing in these newsletters for the last 6 months or so – sustainability of composites and a path to the future that does not include using fossil fuels for either the raw materials or the process energy to make composites. My ingoing title is “Close the Circle, a Roadmap to Composite Materials Sustainability”. I am actually under contract with McFarland for the book, and the manuscript with all of its pieces and parts is due to them by the end of January next year. Now the slog to the finish while I prepare the manuscript along with all of the figures, etc. in the manner that McFarland needs to have it to produce the book. That will take me past the end of this year, so the book will most likely come out late next summer or early fall next year.
Finally, 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, 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.
And just to give everyone a preview of “Close the Circle”, as soon as our daughter and I finish collaborating on cover art, I will be able to give all of you a taste of what the new one will look like.

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