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  • Writer's pictureNed Patton

About Sustainability - What Does it Really Mean?

I’ve written about this topic several times now, so I thought that it was time to provide everyone with a real definition of what Sustainability means with regard to composite materials and the composites industry. As I have said before, Sustainability means different things to different people, primarily because of the lens through which each group sees what they need to do to make their piece of the puzzle sustainable.

And, unfortunately, most of these efforts miss the bigger picture out there. Again, this is because of the nature of composites and the business. The wonderful thing about composite materials is that you have a nearly infinite choice of precursors to use and ways to make your material. This is the main strength of composites and the reason that they are used in so many ways in so many different industries.

This is, as I have said before, also the Achilles’ Heel of composites. And it is the reason that the notion of what sustainability means in the context of composite materials is such a seemingly complex issue. And it is why there are so many disparate notions of what Sustainability means for composite materials.


So, let’s start where most people start – by introducing the concept of a “Circular Economy” for composites. I have talked about this in past posts, but I wanted to take this idea somewhat farther and get to the complete picture of sustainability of composites.

The circular economy is described in various ways, “cradle to grave”, “what comes from the earth gets returned to the earth”, and myriad other ways of describing it. Perhaps a graphical representation of what most people mean by circular economy is appropriate here. This image to the right is sort of a high level overview of what most people think about when they say “circular economy”.


Another representation that has many more words and is much more descriptive of the overall concept is to the left here. This graphic has much more of the representation of what it is going to take to get us to a circular economy in composites. It includes regulatory changes, monitoring progress of companies in their efforts to make their designs sustainable, and also the development of new technologies that will enable the end of useful life composites to be rendered useful again in a form that retains their initial mechanical, physical, and chemical properties. This is of course something of the holy grail of sustainability of composite materials.

And of course, it all starts with transitioning away from petrochemical precursors for composites. That is, effectively, step 1 in making composites sustainable into the far future for the human race, and for our planet.

But, as I am going to describe, it is only Step 1. Once we have made the transition to all biologically based or plant based precursors for all of our composites – even the high performance composites used in the aerospace industry – there is still a tremendous amount of work to do and there are enormous challenges ahead.

The first of these is what to do with end of life composites. How do we separate the fibers from the hardened resins that make them these wonderful materials that they are? This is a very difficult problem, especially if you want to retrieve the resins and reuse them in another composite. There are of course several ways of removing the resin from the fiber. The most common one in use today is to burn away the resin and leave the mostly intact fiber behind. This method has been improved over the years to the point where it now returns fibers that have on the order of 80% or more of the strength and stiffness of the original virgin fiber. But the resin is gone, and all of the nitrogen, carbon, hydrogen, and oxygen that made up the resin has been released into the atmosphere along with some of the other things that are added to resins to give them particular properties. These compounds are not only toxic, they are as bad as greenhouse gas pollutants as the carbon dioxide of car exhaust.

So, we need to develop the technology, chemistry, and techniques to enable the composite recycler to deal with this waste stream, and deal with it at an industrial scale where hundreds of thousands of tons of this material needs to be separated, processed, cleaned, and readied to be reused in either the same or a different application. This is an enormous challenge, but it is one that we must tackle and tackle with all of the resources that we have available to us.

But, this is not the entire story. If we move to a plant-based system of precursors for composites and for most of our structural materials, what will that do to our agricultural systems and will it impact our ability to feed a ballooning population. The answer to this question is less clear.

There is an interesting series on sustainability in the January issue of Scientific American where they talk about this very issue with regard to moving to a plant based plastics industry from a petroleum based industry. The current trend is to grow specific plants for their oils – rapeseed is one of them, flax is another – and to grow them in the quantities required to support the plastics industry of the future. The article brings up several very good points about this transition, and its impacts on the less developed nations where the demand for these agricultural products and the prices they bring on the open market are causing enormous deforestation on both of the major continents in the Southern Hemisphere. These continents are, unfortunately, the places where there are still indigenous populations and where most of the available arable land that has not already been taken over for agriculture resides.

It is apparently that to have a sustainable future for composites and for a plant-based circular economy for composites, we cannot afford to destroy some of the rain forests that are providing us the oxygen that we breathe on a daily basis.

There is also another issue that comes into play when we start talking about agriculture on a grand scale like what will be required. That is the depletion of the carbon in the soils in those agricultural areas that are currently being deforested. In the Northern hemisphere, the means of re-introducing carbon into the soils has been fairly well established over the centuries as developed nations have begun to understand what is required. In areas where there has only been rain forest, if the forest is removed and used for building materials, the soils are very soon depleted of carbon after just a few cycles of planting and harvesting crops.

To summarize, the issues facing us to make composites truly sustainable are many and they are complex. They are also fraught with global politics which is inevitably going to get in the way. What I have described here is what sustainability really means in our global economy. We need to take a holistic view of all aspects of this problem and develop a completely integrated program that cuts across the industry, and passes through agriculture, geopolitical systems, and Governments worldwide. Sustainability is not just development of a circular economy for composites, it is much more than that.

Fortunately, there are several organizations that understand what is needed here, and are working toward solutions for each of the facets of this problem. The article I mentioned in Scientific American does end on a positive note in that this problem has been recognized at the highest levels of science and engineering in most of the developed nations. And, in fact, the European Union is quite a bit ahead of the US in this arena. But we are catching up quickly here in the States.

Thanks for reading this diatribe. I’ll move on to a less controversial topic next time.

And remember, my book is coming out in late June or July, and you can pre-order a copy today either from my website or from McFarland Books directly - https://mcfarlandbooks.com/product/The-String-and-Glue-of-Our-World/

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