solvent for PET and PMMA

goldfish

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Dec 14, 2000, 7:21:09 PM12/14/00

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Dear esteemed colleages,

I'm trying to clean a laboratory injection mold, which
I inherited without the manual (of course). The crucible
and the mandril are steel, I think, or stainless steel. It is
black with accumulated gunk that ends up in the injected
polymer, which I cannot tolerate in my next bath of samples.

Does anybody know of good solvents for PET and PMMA?
Especially: cheap and readily available in a lab, not too
toxic, but dissolves like mad?

Other suggestions for cleaning are welcome.

Many thanks,
Peter Mott

Steffen Maier

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Dec 15, 2000, 4:46:47 AM12/15/00

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There are many good solvents for PMMA (e.g. THF, toluene, CHCl3,...).
PET is less convenient to dissolve: hot DMSO, phenol, chlorophenol,
nitrobenzene....

What about sandblasting???

Best regards, Steffen

Clive A Maier

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Dec 15, 2000, 4:55:55 AM12/15/00

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The usual way in industry of removing plastics residues from metal parts
such as extruder screws is by controlled pyrolysis. You can see one
example at this site - http://www.controlled-pyrolysis.co.uk/ - and it
should be easy to find other suppliers. Alternatives, used particularly
to remove smaller residues from moulds, include laser cleaning -
http://www.jetlaser.de/E/e-index.htm - and dry ice blasting -
http://www.coldjet.com/rubber.cfm.

--
Regards,
Clive Maier

Frank Logullo

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Dec 15, 2000, 8:09:40 AM12/15/00

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Polymer labs I worked in used "salt baths" which I believe were controlled
oxidation. Common solvents are not going to remove char but PMMA is soluble
in acetone and acid or base (better) will hydrolyze PET.
Frank

goldfish <p...@xbt.nrl.navy.mil> wrote in message
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goldfish

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Dec 15, 2000, 9:23:41 AM12/15/00

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Steffen Maier wrote:

> There are many good solvents for PMMA (e.g. THF, toluene, CHCl3,...).
> PET is less convenient to dissolve: hot DMSO, phenol, chlorophenol,
> nitrobenzene....
>
> What about sandblasting???

I do not want to scratch things up much, as I want
to keep the relatively tight fit between the mandrill and
the crucible.

Next thought: soak everything in EtOH + NaOH.
Would that help?

Thanks
Peter Mott

Wouter van Marle

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Dec 18, 2000, 4:48:27 AM12/18/00

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> Does anybody know of good solvents for PET and PMMA?
> Especially: cheap and readily available in a lab, not too
> toxic, but dissolves like mad?

A very good, but pretty toxic unfortunately, solvent for PET is
trifluor acetic acid. It dissolves PET like mad, at room temperature!
But as I said it's pretty toxic, and it's a strong acid - dunno the
pKa but it's towards HCl.

Regards
Wouter

Mike Henry

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Dec 19, 2000, 7:36:32 PM12/19/00

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Would NMP (n-methylpyrolidinone?) work? Seems to me that some one was
looking at NMP to dissolve PET for a recycling scheme.

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Patrick Jarvis

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Jan 12, 2001, 12:00:14 AM1/12/01

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I am new o this news group. I read that someone suggested sandblasting and
another said you should worrie about scratching but there may be 2 other
options. One is called Soda Blasting and the other is utilizing a burnoff
process. Soda blasting works twice as well as sand blasting but does not
pit or cause any etching, if done correctly. We use both these porcesses at
my shop in Alabama. If you have any questions, please email me.

Patrick Jarvis
pja...@dynatechcorp.com

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