In article ,
Al Lorona wrote:

Has anybody noticed that Super Glue (cyanoacrylate clear liquid glue) just
doesn't seem to work any more? I remember when it first came out that it
used to bond anything and everything. Lately, seems that I can't even fix my
son's toys with it any more.

Latest failu Just tried to glue a small 12V DC fan for a PA with it and
the bond came apart the next day pretty much by itself.

There are certain specific plastics (polyethylene, polypropylene, and
Teflon) which most cyanoacrylates will not bond to properly (either at
all, or without some specialized surface preparation). I believe that
these plastics are characterized by low surface energy.

If what I read in some of the trade journals is any indication,
manufacturers have been selecting newer and more specialized blends of
thermoplastics and thermoset plastics over the past few years, in
order to optimize the cost, strength, impact resistance, etc. of their
products. It would not surprise me if you're more likely now, than a
few years ago, to run into plastic-resin blends which cyanoacrylates
have difficulty "getting a grip on".

A web page at Saf-t-lok indicates that "Surface ionization
pretreatment is necessary to affect best results with instant bonders
on non-polar plastic surfaces such as polyethylene or polypropylene.
SAF-T-LOK® Surface Conditioner does the job."

Cyanoacrylates also vary significantly in their "grabbing"
aggressiveness, viscosity, gap-filling strength, and their tendency to
bloom (emit the classic eye-searing white fumes which then "frost" the
surface around the application point). My impression is that the
newer non-blooming formulations may not grab as aggressively, or hold
as strongly as the classic variety. None of them seem to be
particularly good in gap-filling strength, unless you add an
additional particulate filler (baking soda is sometime suggested).

Abrading the surface with fine-grit sandpaper, and then degreasing
with isopropyl alcohol, can improve the grip significantly.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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