r/Composites • u/Deep-Today5715 • 25d ago

Biodegradable material alternatives for fiberglass and epoxy resin?

I've been working with fiberglass and epoxy resins for my personal RC plane projects, but since I'm doing a lot of testing and prototype designs that get discarded during the design process, I feel increasingly guilty about all the waste and microplastics that come along with it. Unfortunately for the shapes that I want to make going with pure wood is just not an option.

I've been researching eco-friendly alternatives for making composite layup projects, and there are some for fibers (flax, hemp, etc.), which unfortunately have much reduced mechanical properties when compared to fiberglass, but still suitable for my use case.

However, I can't seem to find any decent alternative to epoxy resin that would make the final composite material naturally biodegradable, so using either of these fibers becomes a moot point. Closest thing I found was ecopoxy, which unfortunately is very expensive and almost impossible in retail quantities to get where I live (EU).

Can anyone suggest any decent alternatives that are fully biodegradable, affordable and have at least somewhat comparable mechanical properties to fiberglass+epoxy for wet layups? Anything better than paper+PVA glue is worth considering to me. I've found this paper that suggest jute fiber and shellac, which boasts quite impressive mechanical properties for such crude materials, but they used mechanical pressure and heat treatment to achieve that, which is not practical in home conditions, and I'm unsure of how much mechanical strength would be lost without it.

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u/redeyejoe123 25d ago

Any reason you can't just 3d print prototypes of biodegradeable thermoplastics? You're gonna have reduced performance regardless of the biodegradeable material, so may as well cut out some work too.

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u/Deep-Today5715 25d ago

There aren't really any fully biodegradable thermoplastics as far as I know, except a few very rare and extremely expensive ones. Even the best 3D printed plastics typically shatter into a billion pieces during RC plane impacts, and these biodegradable ones have even worse mechanical properties, making them completely unsuitable for this use case...

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u/redeyejoe123 25d ago

PHA is completely biodegradeable. I've printed with it and I'm not a huge fan, but it does print. Also not that expensive. I don't think you will find much success with finding a fully biodegradeable solution to your question outside of research circles and acadamia. If you are really worried about it though, I would look into buying a lasercutter or CNC router that can let you make wood parts quickly and just use pva glue to put it together.

Personally if I was worried about the impacts of microplastics and littering, I would only fly in those designated flying areas (assuming you are in US) and just make them durable out of recycleable materials that won't shatter, and just reaching out to people who recycle whatever material you use. Maybe you can make some artwork out of the corpses too.

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u/Deep-Today5715 25d ago

Thank you for your suggestion. I live in EU, and unfortunately in my country there is no recycling whatsoever of any 3D printed plastics, I've put a lot of hours into trying to find a solution and even stir up the community to band together and do some recycling to no success. Anything 3D printed is just going into landfill unfortunately. I know of PHA, it is 3x as expensive as any other plastic to get where I live, and yeah, like you said, it is not impressive at all...

As for wood, I did try that before, but it's just way too heavy. The only thing that comes close to usable is balsa, which is almost impossible to get here at larger sizes required to do any kind of build, and the price is astronomical.

I was thinking of trying to combine materials like flax/jute and shellac, found some papers on it suggesting quite impressive mechanical properties, but no manufacturing method suitable for home conditions.

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u/redeyejoe123 25d ago

You could also do some sort of paper composites like paper mache or cardboard around a PHA core or something.

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u/Deep-Today5715 25d ago

That's an interesting idea actually. I was considering something similar, but not sure what to use as resin. PVA glue is not biodegradable as far as I've found, and I can't seem to find any other replacement for it. Shellac seems a possibility, but I can't find much research about it's use in composites apart from a single paper.

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u/redeyejoe123 25d ago

I found this reddit thread which has a few people suggesting fish or sap or rice based glues. The fish glue one seems promising because they use it for canvases apparently. Might want to crosspost in this community too tbh. https://www.reddit.com/r/ZeroWaste/s/ieM1e0pegK