Re: Chemical resistance of PTFE against hydrochloric acid  


Posted by Diffusion Polymers on November 17, 2005 at 11:09:58:

In Reply to: Chemical resistance of PTFE against hydrochloric acid posted by Eric Li on November 16, 2005 at 16:54:36:

Dear Eric Li,

An increase of temperature, increases the diffusion coefficient [D: m2/s] and the chemical corrosion rate [k: m/s]. This effect can be described with the Arrhenius law.

The pressure does not have an influence on the two described rate constants, nor does it have an influence on the Solubility for diffusion or on the Hydrochloric acid concentration as liquids are hardly compressible.

However a pressure increase with a factor 2 forces 2 times as much liquid through the PTFE liner (Maxwell Stefan equation). This will lead to a chemical degradation rate increase with a factor 2 when there is a first order corrosion rate dependence on the Hydrochloric acid concentration.

If you could state the exact Hydrochloric concentration that you are interested in, including the process conditions, then we are able to do the calculations. Perhaps Hydrofluoric acid is also of interest.

Best Regards,

 


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