Re: Patching TPU innertube

On 12/22/2024 8:30 PM, James wrote:

I got a snake bite puncture on one of my TPU innertubes.  I haven't bought one of the commercial patch kits, so I thought I would try a blob of Aquaseal.  Known for it's usefulness in repairing neoprene stuff and more, I thought I would give it a go.
 I tried to rough up the TPU innertube surface, but the sandpaper didn't seem to have much if any effect.  I cleaned it with a little Windex, and after that had dried and I had rubbed it some more with clean tissue paper, I applied a drop of Aquaseal to each hole.
 I have the stuff that takes about a day to solidify.  I left the tube undisturbed for at least 12 hours, though I can't recall exactly how long, before putting it back in the wheel and inflating.
 This is on my gravel bike, with 40mm tyres that I inflate to 40-45psi.
 The repair has held for a few hundred kilometers at least, and now I have put different tyres on the bike, so I inspected the repairs.
 The blobs of glue seem to have spread and flattened a bit, but otherwise have appeared to bond well and not leaked.
 

Good choice. I knew nothing about the subject before snooping around just now. It seems Aquaseal active ingredient is methylenediphenyl diisocyanate which is compatible to TPU polyurethane.
https://www.nrs.com/assets/downloads/msds/msds%202291%20aquaseal.pdf
https://polyurethanes.basf.us/files/pdf/2019-MDI-Handbook_EL.pdf
Making a reliable bond unlike a simple contact adhesive such as a stick-on patch.
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Andrew Muzi
am@yellowjersey.org
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