Super Glue Science

[CoachBob]

I know there are chemists on this site because I get corrected by them with uncomfortable frequency. But that's another story.

My question is about super glue and closed cell foam.
The background of the question starts with mee sitting in a 2006 tying show making foam flies with super glue. [See http://www.flytyingforum.com/pattern6910.html for the pattern I was tying]. Sitting next to me was a PhD chemist who explained that the reason super glue worked so well was that it caused a chemical reaction with the surface molecules of the closed cell foam -- and then he went into chemistry that lost me completely. Like I said, that's another story. Anyway, I had been using super glue for closed cell foam for quite a while and knew what it did, just not why.

So...here's the question.
What is the chemical reaction between super glue and closed cell foam
and...is it as permanent as it seems?

[jimsnarocks]

CoachBob, I don't know why it works either but it sure speeds up the tying time and holds the foam to everything from the thread on the hook to foam to foam. I'm tying up some foam hoppers for a fly swap and I'm using the heck out of it. Jim

[Normand]

So...here's the question.
What is the chemical reaction between super glue and closed cell foam
and...is it as permanent as it seems?

water

http://science.howstuffworks.com/question695.htm

http://www.waynesthisandthat.com/spuerglue2.htm

http://www.ehow.com/how-does_4570225...glue-work.html

[DDRRedneck500]

ive always heard it was water that causes superglue to harden. this would explain why it would glue so effectively youre fingers together. it reacts with the water in youre skin(or in most cases the water vapor in the air) which causes it to harden.

[Black pennell]

I am sure it is to do with moisture as superglue was created during the vietnam war for sealing injuries so as to prevent infection.

[bspitt]

Coach Bob?Chemist Here ..guilty as charged!!!

Superglues or "cyanoacylates" are cure by the crosslinking (polymerzation) of their reaction with weak bases..(water, aochol, blood, etc) So when you glue your fingers together..You are actually crosslinking the very thin layer of moisture on one finger to the very thin layer of moisture on the other finger?Hense making a Bridge between the two fingers..which can easily be broken ..depending upon how much dry dead skin you have. This is why super glue bonds wounds very well..all the presece of blood & bodily fluids to react with .

Now to the closed cell foam.. Craft foam is a polyurethane closed cell foam. It is a polyol (weak base) resin reacted with an isocyanate..the isocyanates are similar chemisty to the super glue. So not only does the super glue react with the thin layer of moisture on the foam, but it actually crosslinks with the polyol resin (left over unreacted sites) within the foam..so the Bond is much greater and will hold better and longer. You will proabably see a failure in other areas of the foam before the foam - super glue- foam bond breaks.

Hope this help _ I could write a whole essay on this--but it would bore everyone to death!!

Thanks
Brannon

[MontanaMoose]

I've got a question bspitt, is it really true that for sealing cuts we should buy 'medical grade'
SG?

Cheers,

MontanaMoose

[Normand]

my doctor used "medical grade" for closing the cut in my chest after he put in the defibrillator/pacemaker

[bspitt]

I've got a question bspitt, is it really true that for sealing cuts we should buy 'medical grade'
SG?

Cheers,

MontanaMoose

I'm no doctor..But I did stay in a Holiday inn express last night?.

I would suggest staying with medial grade for wounds, but I suspect that it is not much differnet..just a good way to charge more? mabe a little differnet solvent or carrier to help out with the "sting."

BP

[CoachBob]

Very cool
Thanks.