I have some plastic soda bottles (polyethylene terephthalate) which I would
like to convert to flat panels for a project. I have cut some up and tried
to glue them in place flattened out, but their curvature causes them to stress
the glue as it cures, which I'd like to try to avoid. I could clamp them down
but that's more trouble than it's worth, for the number of panels I'd have to
clamp down.

If I flatten PETE panel cut-outs under a brick, and then heat them to just
below their melting point in that position, will they reshape themselves flat?
Or would I need to actually melt them down (which should be possible, as PETE
is a thermoplast, and actually preferable in some ways, as I'd be able to use
the entire bottle mass)?

Important ancillary question: does PETE outgas significantly when heated,
either to just below melting, or just above melting? This will determine if
I can melt them in my indoor shop, or if I'll have to do it outside. My wife
keeps many reptiles (snakes, geckos) in the house, which are extraordinarily
sensitive to airborne toxins. We cannot cook using nonstick surfaces, or use
insecticides anywhere in the house, even with much ventilation, or they get
sick (or die, since some of them are already of dubious health -- my wife is
a herpetological verterinarian, and many of the snakes are "patients").

Date: Tue, 26 Aug 2003 18:55:48 -0700

PET bottles are blown into a mold. Look between crossed polarizers
(two apir of Poalroid sunglasses crossed black, bottle between) to see
if there is residual strain. PET transparencies (Mylar) are the same
stuff. In theory you could heat the PET above its glass transition
temp, reshape it, and cool it before removing the mold. In practice,
blow-molded polymers often shrink nastily when rendered hot and
rubbery. If you heat to its melting point you won't need glue.

PT outgasses acetaldehyde if you treat it hotly and unkindly. It's a
concern in hot-bottling or sterilizing stuff.