Recycling Epoxy

[Sparweb]

Finally - it's possible to break down epoxy and recover/recycle significant parts of it, along with any reinforcing fibers that might be in the matrix.

https://www.nature.com/articles/s41586-023-05944-6

I haven't posted anything chemical before. To my eyes this is a convincing proof of concept. Thoughts?

 

[btrueblood]

So...some 50% by weight of the resin is decomposed to re-usable BPA, is the remainder in a disposable form? Did not see numbers for catalyst consumption/recovery, maybe I overlooked it. Ruthenium is running north of $400/oz; recovery of the catalyst is going to be a big part of whether the process is economical.

 

[EdStainless]

I have seen chemical companies that make epoxy doing this.
they have the equipment and knowhow.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[Sparweb]

The article states that the catalyst is re-usable, and the reaction seems to proceed as long as there is feedstock.
The recovery % seems to be the progress "so far" after a set period of time, however I notice in the article the time allowed for some reactions varied. Like, 12 hours sometimes or days for other trials. Little discussion of optimal temperature, or even trying various temperatures to see if the reaction is faster/more complete.
This was a proof of concept, so they surely already know that they have a long way to go yet with a process such as this.
And paying for the Ruthenium catalyst probably burned up most of the budget.

Where would you guys go from this point? Seek funding for larger batches or try to find a catalyst that isn't so pricey?

 

[btrueblood]

I think I like the idea of mapping temperature/time and probably type of epoxy for multiple trials (including a few to verify repeatability?). Could keep things small scale and just look for optimums, also look for catalyst burn-up/poisoning. Testing other catalysts might be viable, but I'm not smart enough to know if that can work, most less-noble catalysts are going to oxidize when breaking CO bonds? It would be interesting too, to see some attempt at an economics analysis - compare the costs to recover x kg of base resins, compared to cost of virgin stock.

 

[Compositepro]

Recycling has becomee a religion to many. The question is can bisphenol-A be made more efficiently from old epoxy than from petroleum. The answer is no. Epoxy resins are an incredibly diverse family of polymers with the epoxy component often making-up less than half the formulation. Recycling to any liquid hydrocarbon allows it to be added back to crude petroleum, which then goes to making more epoxy or gasoline. Who cares which? Only the religion cares.

 

[Sparweb]

I think I get your point about the true believers, but is it really that simple?
Coming from the aviation industry we're usually a small niche in almost everything we do, except for the major airframe OEM's. They get a lot of scrutiny and media attention. As these OEM's aim for greater use of composites (0% recyclable) instead of aluminum (~100% recyclable) they could be exposing themselves to a new public image problem. Then there are the zillions of electric plane start-ups that want to make every piece of their structure in monolithic resin-transfer molds - they will want to green-wash their materials just as much as their fuel source. If they could say something sensible and realistic about material recycling that could help their image, they will.

Setting aside the woo-woo crowds, and if we can agree that reducing the consumption of resources is a worthy goal, then I see value in recovering the matrix AND the fibers for reuse. Perhaps this depends on whether one expects petroleum to rise in price quickly or slowly in the future. High commodity prices usually favour recycling of any material, of course.

 

[btrueblood]

I think the idea of recycling composites to reduce/eliminate the void space in land fills is not a bad idea. As is minimizing small fiber particulates (though releasing these from the epoxy binders currently trapping them just means you need to find a new way to safely dispose of them).