Plastic Compatibility with TMAH

[GunT]

Hi,
Hi,

I have posted the same post at Chemical Engineering Forum. So I apologize for the duplication. But there was no response in that forum so I am posting it here.

I am looking for compatible plastics (PFA, PTFE, ECTFE, PVDF, PEEK, TFM) with:

1. 25% Tetra Methyl Ammonium Hydoxide- TMAH aqueous solution at 90 deg C
2. 25% TMAH solution in methanol at 90 deg C
3. 25% TMAH squeous solution + small amount of Glycidol Ether (surfactant).

I appreciate any help I can get.

Regards,

 

[patprimmer]

Are you asking if any of the above plastics are resistant to the above chemicals.

PTFE is about as chemical resistant as plastics get. It should be compatible with all of the chemicals.

DuPont will be able to provide extra information including chemical resistance charts.

Regards

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[Demon3]

Yes, PTFE should resist it all but is rather expensive. When you want resistance data for one, not so common chemical you will just have to do the tests yourself. That kind of data does not exist for all combinations of polymer/chemical/temperature.


There is not any memory with less satisfaction than the memory of some temptation we resisted.
- James Branch Cabell

 

[GunT]

Thank you both for the replies. I have contacted Dupont and other plastic manufacturers about the chemical compatibility. They are using "Chemical Resistance Guide for Plastics" by Compass Publications as reference. I have access to that book too. But we are having a discepancy between what the book says and our field data.

According to the book, PVDF is compatible to 100% TMAH until 93 deg C. But in the field we are having problems with 12% TMAH at 65 deg C.

I am looking for anyone with field experience working with this chemical and related plastics. Yes PTFE may be the most chemical resistant species in the universe, but I want to verify if PTFE is resistant to this particular chemical.

Regards,

 

[patprimmer]

That is easy.

Get a sample of the reagent.

Get some samples of the plastic and weigh each.

Record the weights.

Get a stainless steel jig to stress the plastic.

Get a thermostatically controlled water bath.

Get a glass or stainless steel beaker.

Insert one sample of plastic in jig with plastic stressed.

Put stressed and unstressed samples in beaker.

Set water bath to desired temperature.

Fill beaker with reagent to safely cover samples.

Leave test run for prescribed time.

Weigh the samples after rinsing and air drying.





Regards

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