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Acrylic cracking due to adhesive solvent
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Mike d
Apr 25, 2012, 3:16:20 AM4/25/12
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Is the cracking due to localised swelling of the plastic, or is there something
else going on? Is there any pre-treatment that can prevent it happening?
Whilst building an outdoor enclosure for electronics, I discovered the hard way
that acrylic and polycarbonate have poor resistance to the solvents used in the
adhesives and sealants commonly available from hardware stores. Finding
something that sticks well to acrylic and other common building materials,
doesn't cost a fortune and is available to the public is a challenge.
Aside from solvent welding, I've only found 2 products which stick. One is a
moisture cured silicone/polyurethane and requires an expensive primer ($60
minimum purchase) which as far as I can tell effectively welds with and replaces
the surface to which the sealant bonds. Without the primer there is minimal
adhesion.
The other is marketed as an underwater pool repair epoxy with no specific
mention of acrylic or polycarbonate although people report that it does work OK
in aquarium applications.
Is there an affordable pre-treatment that will make it work with regular
silicone or non-solvent polyurethane sealants?
Mike
else going on? Is there any pre-treatment that can prevent it happening?
Whilst building an outdoor enclosure for electronics, I discovered the hard way
that acrylic and polycarbonate have poor resistance to the solvents used in the
adhesives and sealants commonly available from hardware stores. Finding
something that sticks well to acrylic and other common building materials,
doesn't cost a fortune and is available to the public is a challenge.
Aside from solvent welding, I've only found 2 products which stick. One is a
moisture cured silicone/polyurethane and requires an expensive primer ($60
minimum purchase) which as far as I can tell effectively welds with and replaces
the surface to which the sealant bonds. Without the primer there is minimal
adhesion.
The other is marketed as an underwater pool repair epoxy with no specific
mention of acrylic or polycarbonate although people report that it does work OK
in aquarium applications.
Is there an affordable pre-treatment that will make it work with regular
silicone or non-solvent polyurethane sealants?
Mike
dlzc
Apr 25, 2012, 10:12:33 AM4/25/12
to
On Wednesday, April 25, 2012 12:16:20 AM UTC-7, Mike d wrote:
> Is the cracking due to localised swelling of the
> plastic,
Swelling as the solvent is applied, then shrinking again as the solvent leaves the matrix, leaving the outside first.
> Is the cracking due to localised swelling of the
> plastic,
> or is there something else going on? Is there any
> pre-treatment that can prevent it happening?
David A. Smith
Marshall Dudley
Jun 13, 2012, 12:03:59 PM6/13/12
to
This is referred to as stress crazing. You can read about it here:
http://scanscience.com/files/crazing.pdf
It is caused by the absorption of the solvent on the surface of the
plastic causing it to expand which stresses and cracks due to the stress
on the core which does not expand.
Marshall
http://scanscience.com/files/crazing.pdf
It is caused by the absorption of the solvent on the surface of the
plastic causing it to expand which stresses and cracks due to the stress
on the core which does not expand.
Marshall
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