Random Science Fact#1: Rhodamine B will stain Polyetheretherketone

Sometimes in lab there will be an interesting result that would be good for fellow scientists to know but is not worth even considering publishing. In that spirit, I bring you random science fact.

In the course of experiments, it became prudent to determine whether Rhodamine B will stain an apparatus made out of PEEK (polyetheretherketone), which is a rather good chemical resistant material. I prepared a 1M Rhodamine B solution in DI water (not all Rhodamine B dissolved by the way) and spun it in an apparatus completely made out of PEEK in conjunction with my undergrad colleagues.

PEEK


PEEK’s chemical structure is shown above.

Rhodamine B did appear to stain PEEK, where the PEEK had been poorly machined and there were small grooves for Rhodamine B to collect in. Cleaning with a 1M HCl solution and some intense elbow grease action cleaned the Rhodamine B off the PEEK very well. However, the crazyglue that was used to piece together some of the PEEK pieces were permanently stained and no amount of HCl seemed to be able to remove the stain.

This has been a Random Science Fact

Mitch

3 Comments

  1. Hi Mitch,

    Do you have any experience with PEEK and concentrated HCl or sulfuric acid?
    Do you think those acids will damage the PEEK?

    Thanks,
    Paulo

  2. Hello Paulo and Mitch,

    If you will use concentrated sulfuric acid, take care because this will dissolve the PEEK after some time. The sulfonation with 95-98% sulfuric acid is well known in the scientific community. Normally you can use 500 ml of 95-98% sulfuric acid for 25 grams of PEEK powder. From Wikipedia I got this information:

    PEEK performance in acids is very dependent on the type of acid – it shows poor resistance in concentrated sulfuric, nitric, hydrochloric, hydrobromic and other mineral acids (though performance may be adequate for short term use with these acids in very dilute form). Its resistance to hydrofluoric acid and oleum is very poor. PEEK shows good resistance to phosphoric acid and organic acids (acetic, citric, oxalic, tartaric etc.), but varying resistance in the presence of halogens. PEEK is resistant to dissolution by some aldehydes and ketones such as acetone, but not (at higher temperature) methylethyl ketone.

    http://en.wikipedia.org/wiki/PEEK

    See ya!

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