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I would like to fill a long, airtight hollow body (like a big tube) by injecting expansive foam ... and I'm looking for an alternative to polyurethane because it doesn't work.

Indeed; polyurethane is not satisfactory for this use (in addition to being very disgusting to use but I already knew that) because it seems that it visibly does not expand and dry properly inside of the tube ... (solvent saturation? Pressure?)

It works close to the openings (where we inject and where the solvents can evaporate I imagine ...) but inside it remains "soft" and there remains a kind of glue after a few hours ... It seems that the capacity drying (solvent evaporation) is limited to about 15-20 cm thick?

There is no information on the manual about the maximum thickness ...

A solution would be to proceed by layer of 15 cm but that would mean that it is necessary to use X bomb of PU (a bomb can be used a few minutes, after it is screwed up for those who do not know) ... so I prefer to find a best product!

Some propeller manufacturers use foam suitable for hollow and long bodies, I found this on a manufacturer's site:



And I imagine that this foam, used in a carbon propeller, is much more rigid than PU foam because the carbon envelope of the propeller is insufficient to maintain its resistance.

Anyone have any idea what product it is? A brand? A product name?

Thank you friends!

ps: funny thing, my cat was very intrigued or very suspicious by the expansive foam when it was still moving ... where was it maybe just the smell?

Christophe wrote:It looks like the drying capacity (evaporation of the solvent) is limited to about 15-20 cm thick?

Ah, I finally found a notice that talks about thicknesses: http://fra.sika.com/dms/getdocument.get ... -combi.pdf

It is even worse than 15 cm since this notice speaks of 5 cm ...

- Apply in layers up to 30 mm thick.
- The consistency of the foam is suitable for filling vertical joints up to 5 cm in width.
- Cavities or joints greater than 5 cm in width must be filled in successive layers applied to the previous ones, completely polymerized

So if I can't find another product ... I'm good at making several layers and my piece to be filled is 60 cm long, it's not won! It sucks!

I found this * to fill the hollow body, then we would have to find a glue binder ** ... I don't know.
After, I didn't see your play ...

* https://www.kenzai.fr/graphite/1913-iso ... m-026.html
** https://www.isosphere-industrie.com/col ... e-aqueuse/

Thank you but it does not seem very suitable I am trying to improve the mechanical properties ... not insulating ...

Here is another carbon propeller in "section" (involuntary oops): there is a white material inside ...



But what is it?

Maybe a resin https://www.boutique.resines-et-moulage ... -2080.html

Ah yes it is quite possible that it is that!

Thank you Izy!

Christophe wrote:But what is it?

I could be wrong, but I do not have the impression that these foams have a role in improving the mechanical properties (the woven carbon is already extremely solid), but rather as an insulator which prevents the part from entering. resonance, a bit like for skis whose sparkling soul only filled a box for these same reasons.

Possible ... but the epoxy resin with a bin matrix is ​​tough, it's 1 of the 2 resin (with polyester) used to make carbon parts!

ps: your avatar kidding?

Christophe wrote:
ps: your avatar kidding?

Not at my house, no.
If not, what's your "fill-in" room? Can we have a photo, as soon as an idea germinates?