[Jman]

I heard about some very strong glue for bonding natural Latex material. It's apparently Latex dissolved in Hydrocarbons. The source of this glue won't ship due to the Hydrocarbons. So curious if it's at all possible to make it? Or does it require a decent lab set up?

I tried dissolving it is some thinners which is 30-40% Toluene & after a week it still did not degrade. I assume there would be challenges like trying to get the right consistency?

Would like to know how such a glue gives a very strong bond? Some have said even without scratching/sanding the surface. Does the solvent melt the two together?

thanks

[Enthalpy]

Just cyanoacrylate glues natural rubber very strongly. For reasons obscure to me, the bond doesn't break under rubber elongation.

Try other solvents instead of toluene. Isoalkane mix is sold as a general solvent and paint thinner. Petroleum, turpentine, hexane. Alcohol and acetone dissolve it too, but do they make chemical changes? The right consistency must be rather thick, hence with much solid dissolved.

Yes, solvent glues do dissolve the parts' surface, which tells why cleanliness is less vital for them, and why they are often efficient. I used straight acetone on ABS, without dissolving some plastic in advance, and it works nicely.

[Arkcon]

What you've described is rubber cement -- a solution of natural latex in gasoline.  Smells bad, but it works.  Like Enthalpy: said, we have more advanced things these days.

[Jman]

Just cyanoacrylate glues natural rubber very strongly. For reasons obscure to me, the bond doesn't break under rubber elongation.

Try other solvents instead of toluene. Isoalkane mix is sold as a general solvent and paint thinner. Petroleum, turpentine, hexane. Alcohol and acetone dissolve it too, but do they make chemical changes? The right consistency must be rather thick, hence with much solid dissolved.

Yes, solvent glues do dissolve the parts' surface, which tells why cleanliness is less vital for them, and why they are often efficient. I used straight acetone on ABS, without dissolving some plastic in advance, and it works nicely.

Thanks Enthalpy for your help. I think Petroleum & certainly Turps would leave some oily residue behind, might go with acetone as it's readily available.

[Jman]

What you've described is rubber cement -- a solution of natural latex in gasoline.  Smells bad, but it works.  Like Enthalpy: said, we have more advanced things these days.

Not sure about more advanced glues. The bond has to be very strong, I have seen glue joins by latex tailors that are impossible to tear apart without damaging the bulk of the latex pieces. They simply are incredible.

[Jman]

Well in experimenting I think I'm doing something wrong, because I have tried 100% acetone in glass sealed jars & after a few days to a week of sitting in the solvents, the majority of the latex is still present, partially damaged & old looking, but thats it.

Maybe it takes weeks? I might try simple Petrol.

[Intanjir]

Pure acetone doesn't seem ideal as it is fairly polar while polyisoprene is not at all polar. Of course natural rubber is found in a polar aqueous medium and we associate latex paints with water-based solvents. However natural rubber is a suspension and not a solution. I would expect an ideal solvent for it to be at most only very weakly polar. So pure toluene should probably work reasonably. You said you used 40%. Was the other 60% something polar?

You will have trouble getting a solid piece to fully dissolve as it has been vulcanized to some extent. Thoroughly shredding it should help some. However devulcanization is at least economically non-trivial as scrap rubber is generally repurposed for other uses and not recycled.

The glue you describe may be more than a rubber cement analog. If you can swell the crosslinked pieces of rubber you want to join with a solvent containing initially uncrosslinked rubber which could crosslink somehow as a cure then you would have a nice bond.

[Jman]

Pure acetone doesn't seem ideal as it is fairly polar while polyisoprene is not at all polar. Of course natural rubber is found in a polar aqueous medium and we associate latex paints with water-based solvents. However natural rubber is a suspension and not a solution. I would expect an ideal solvent for it to be at most only very weakly polar. So pure toluene should probably work reasonably. You said you used 40%. Was the other 60% something polar?

You will have trouble getting a solid piece to fully dissolve as it has been vulcanized to some extent. Thoroughly shredding it should help some. However devulcanization is at least economically non-trivial as scrap rubber is generally repurposed for other uses and not recycled.

The glue you describe may be more than a rubber cement analog. If you can swell the crosslinked pieces of rubber you want to join with a solvent containing initially uncrosslinked rubber which could crosslink somehow as a cure then you would have a nice bond.

Hi, The solvent I used that did nothing to the latex is 30-40% Toluene, 30% naptha, 20-30 % Acetone.

I will try shredding the latex.
Another solvent is 60-70 toluene, 20-30% methyl ethyl ketone, 10-20% naptha.
Anything I can add to the pure acetone?
thanks

[Intanjir]

That is a thoroughly hydrophobic mixture. If that does little to your rubber then I would guess that it is too crosslinked to be significantly dissolved. You will at best be able to swell a thoroughly crosslinked sample, but without being able to break the crosslinks you will not get dissolution.

[Intanjir]

Uncut hardware store toluene is probably approximately as good a solvent for rubber as anything else. Toluene's hansen solubility parameters match up very nicely with the best values I can find for poly(isoprene) and it swelled up some rubber surgical tubing about two fold in about an hour. I had soaked another piece of tubing in mineral oil overnight and only saw about 40% swelling.

I am skeptical whether significant amounts will dissolve as it is still quite cohesive despite the large swelling. I am not sure whether there are any common products which use rubber which is sufficiently uncrosslinked for a simple dissolution without reaction. But if you can find such rubber, toluene will likely dissolve it.

[Enthalpy]

The glue used to repair bicycle tubes could give a hint. Its consistency suggests it does contain some dissolved elastomer (latex rubber?). Though, in 10min it certainly doesn't dissolve a hole through the tube: it dissolves or reorganizes a thin layer of elastomer, just enough for good adherence.