Aeropoxy question

I have some aeropoxy resin and hardener. It is the one that mixes at a 27 to 100 ratio. Is this adhesive for gluing fiberglass parts together or is it for laminating fiberglass cloth?

Looks like laminating epoxy.
https://m.aircraftspruce.com/catalog/cmpages/aeropoxy.php?clickkey=23228

But it certainly can be used for gluing parts together. The nice thing about it is you control the additives.

Additives? Like fillers?

Yes, fillers to increase toughness or viscosity, fillers to reduce density.

Just for my education, are there other additives?

When mixed, laminating epoxy is about as thick as cooking oil and penetrates fibers quickly. Adhesive epoxy is usually somewhere between cold corn syrup and clay.

rocketcharlie said:

Just for my education, are there other additives?

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The big 4....

- Adhesive/thickener filler (West 404) for making epoxy thicker and less brittle
- Coloidal silica (West 406) thickens epoxy so it won't run
- Milled glass or similar fiber makes epoxy stronger
- Microballons make epoxy easier to sand.

With those, you can make epoxy do whatever you want. I never use structural epoxy - only laminating epoxy and the above fillers.

Jim

JimJarvis50 said:

The big 4....

- Adhesive/thickener filler (West 404) for making epoxy thicker and less brittle
- Coloidal silica (West 406) thickens epoxy so it won't run
- Milled glass or similar fiber makes epoxy stronger
- Microballons make epoxy easier to sand.

With those, you can make epoxy do whatever you want. I never use structural epoxy - only laminating epoxy and the above fillers.

Jim

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Jim, based on your successes, your advice should be taken to heart by anyone who uses epoxy to build rockets.

I will admit...I'm lazy...I usually just reach for the talcum powder. I'd have to stand up and walk around a table to get the microballoons. Smells nice. It does seem to take a lot of talc to make a paste from laminating epoxy, though.

prfesser said:

Jim, based on your successes, your advice should be taken to heart by anyone who uses epoxy to build rockets.

I will admit...I'm lazy...I usually just reach for the talcum powder. I'd have to stand up and walk around a table to get the microballoons. Smells nice. It does seem to take a lot of talc to make a paste from laminating epoxy, though.

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I go over to West Marine (one of my least favorate stores), pick up some silica and microballons (the West version), and say "please charge me 50 bucks for these two canisters of air". And they do....

The idea is to mix as little epoxy as possible to minimize consumption of the epoxy, and these fillers.

Jim

I use the ES6209 (which does not require additives) for bonding; it mixes 1:1 by weight. Laminating epoxy is for wetting out fiberglass cloth.

Do you all feel that laminating epoxy has the same strength as adhesive epoxy, say for attaching fins?

rocketcharlie said:

Do you all feel that laminating epoxy has the same strength as adhesive epoxy, say for attaching fins?

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No, not without additives. But it’s strong enough once you add the right stuff.
You would never use plain laminating epoxy for gluing without amendments; it would pour right through.

Jim, I missed your reply. I think my question has been answered, now to get a 2nd mortgage for the micro balloons, etc

Jim, I missed your reply. I think my question has been answered, now to get a 2nd mortgage for the micro balloons, etc

Thank you everyone

rocketcharlie said:

Jim, I missed your reply. I think my question has been answered, now to get a 2nd mortgage for the micro balloons, etc

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If you avoid the West branded products, you can get milled glass, fumed silica and microballons without excessive cost. I think the West 404 high density filler is particularly useful, though, as my belief is that it makes the laminating epoxy a better glue (it's for "bonding hardware" in West terminology). Like Steve said, with the appropriate fillers, it is strong enough. At that point, in my experience, it is helpful to be able to control the properties, thickness and shape of the epoxy, and that's why I use laminating epoxy will fillers.

Jim

rocketcharlie said:

Do you all feel that laminating epoxy has the same strength as adhesive epoxy, say for attaching fins?

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I'm not sure how additives change this, but in a lap shear test ES6209 is about twice as strong as unthickened PR2032. So I use each for the task it was designed for.
https://jcrocket.com/adhesives.shtml#test1

JohnCoker said:

I'm not sure how additives change this, but in a lap shear test ES6209 is about twice as strong as unthickened PR2032. So I use each for the task it was designed for.
https://jcrocket.com/adhesives.shtml#test1

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One question that I have not been able to find an answer to is whether ES6209 is filled or unfilled. I would suspect it is filled, as it is a 1:1 mixture. If that is the case, then comparing the filled ES6209 against the unfilled 2032 is perhaps not a fair comparison. It would be interesting to see how filled 2032 would compare. Just curious, have you ever tried ES6209 with silica?

Jim

JimJarvis50 said:

One question that I have not been able to find an answer to is whether ES6209 is filled or unfilled. I would suspect it is filled, as it is a 1:1 mixture. If that is the case, then comparing the filled ES6209 against the unfilled 2032 is perhaps not a fair comparison. It would be interesting to see how filled 2032 would compare. Just curious, have you ever tried ES6209 with silica?

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I suspect you are right about the bonding epoxy being thickened, but I haven't investigated it nor run any tests. I don't mind keeping and using both kinds because I find it easier to use the bonding epoxy, dispensing it from squeeze bottles.

This is conjecture...but there are so many different types of epoxies, reactive diluents, and curatives, that for a 1:1 (or any other desired) ratio, a company would need merely to select the appropriate epoxy and curative, or possibly blend different resins or different curatives together. My copy of Lee and Neville's "Epoxy Resins" is over 60 years old, yet Chapter 1 lists about 50 typical commercial epoxy resins with equivalent weights from 170 to 4000. Each of the following four chapters describes one class (functional group) of curative, and has many examples of each. By now there are surely hundreds if not thousands of different commercial resins and curatives.

Epoxy fillers are solids, and the product would be opaque.

Best -- Terry

prfesser said:

Epoxy fillers are solids, and the product would be opaque.

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The ES6209 white resin is nearly opaque and the yellow hardener is translucent. Note that the hardener is more viscous than the resin so it may be that there are thickeners in it, but it's not obvious.

Can PR2032 / PH3660 be Used with Fillers?
The answer is yes. The AEROPOXY system works very well with the addition of microballons, cotton floc, milled fibers, and many other fillers adding excellent diversification. Having said that, PTM&W developed the AEROPOXY line of resins with specific uses in mind, i.e., laminating resins for composite laminates, pourable and paste adhesives for structural bonding and a lightweight filler for finish sanding, lightweight fillets and build-up of non-structural areas.
https://www.ptm-w.com/aeropoxy/aeropoxy-faq.html#7

However, they don't list mechanical properties for PR2032 thickened for use as an adhesive, so I'll stick with the formulation meant for that purpose. Note that there are a couple of choices for adhesives:
https://www.ptm-w.com/aeropoxy/aeropoxy-adhesives.html