Sometimes you have to apply new epoxy to older cured epoxy resulting in
a "secondary" bond held only with mechanical interlocking to surface
roughness. Is there any way to de-cure just the surface of epoxy so
you can get a chemical bond?

wrote:

Sometimes you have to apply new epoxy to older cured epoxy resulting in
a "secondary" bond held only with mechanical interlocking to surface
roughness. Is there any way to de-cure just the surface of epoxy so
you can get a chemical bond?



No
paul oman
progressive epoxy polymers, inc.

-

Does warming the old stuff do any good?

"No" is not a satisfactory answer.

This past year I have done a little experimenting on this topic for an
application at work. Specifically, we have been experimenting with
using various polymer films to smooth optical surfaces. Such films can
produce roughness below 3 angstroms due to their surface tension.
HOWEVER, after use, we need to be able to remove the films. We have
tried polymer films with various solvents such as acrylic lacquers,
epoxy based lacquers and even polyimide films. Epoxy is nice because
it is fairly hard and is not as easily damaged by heat as the acrylic
lacquers. Cured epoxy can be removed by strong methyl chloride
solutions, especially when heated so I wonder what TCE (Tri-chloryl
ethylene or cleaning fluid) would do.
Polyimide is another story. It was devised as a very heat resistent
and radiation resistant film. When I asked the manufacturer about
removing the cured film he thought I was crazy saying "It isnt EVER
supposed to be removed" and so far he is right. It is great stuff but
requires about 450 degrees F to cure. It makes a beautiful film with
ultra-low roughness that is very adherent to metals.

wrote in message
ups.com...
"No" is not a satisfactory answer.

But what if it is the only answer. I mean, the epoxy is changing chemically,
so it is perfectly feasible that, once cured, it will not be chemically
active to uncured epoxy.

Maybe compare it to "cured steel". Once turned into rust, you cannot weld
new steel to it.... :-)

Meindert

wrote:
This past year I have done a little experimenting on this topic for an
application at work. Specifically, we have been experimenting with
using various polymer films to smooth optical surfaces. Such films can
produce roughness below 3 angstroms due to their surface tension.
HOWEVER, after use, we need to be able to remove the films. We have
tried polymer films with various solvents such as acrylic lacquers,
epoxy based lacquers and even polyimide films. Epoxy is nice because
it is fairly hard and is not as easily damaged by heat as the acrylic
lacquers. Cured epoxy can be removed by strong methyl chloride
solutions, especially when heated so I wonder what TCE (Tri-chloryl
ethylene or cleaning fluid) would do.
Polyimide is another story. It was devised as a very heat resistent
and radiation resistant film. When I asked the manufacturer about
removing the cured film he thought I was crazy saying "It isnt EVER
supposed to be removed" and so far he is right. It is great stuff but
requires about 450 degrees F to cure. It makes a beautiful film with
ultra-low roughness that is very adherent to metals.

What does this have to do with the original question?

wrote:
"No" is not a satisfactory answer.

If it's correct, it is.

Meindert Sprang wrote:
wrote in message
ups.com...

"No" is not a satisfactory answer.


But what if it is the only answer. I mean, the epoxy is changing chemically,
so it is perfectly feasible that, once cured, it will not be chemically
active to uncured epoxy.

That's exactly correct.