Remedy for softened plastic

Discussion in 'General Science' started by tracecom, May 12, 2015.

  1. tracecom

    Thread Starter AAC Fanatic!

    Apr 16, 2010
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    I have a plastic housing for an external HD. At some point (months and months ago,) I used some "cleaner" on the case, which caused the plastic to become sticky. I don't know what the cleaner was...maybe "Oops" or something like that. Is there any way to reharden the surface? Thanks.
     
  2. Kermit2

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    Feb 5, 2010
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    probably not. using heat could drive off the volitile solvent responsible BUT would also be likely to create warpage, cracking and other problems for the plastic housing. if you want to try keep it below 140-130 F, or try strong sunlight exposure on a window sill, not inside a car :)
     
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  3. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    There are a variety of MSDS formulations for OOPS product. Some contain acetone, which will attack many plastics even when in low concentration. It is quite volatile, and I don't think that it would lead to stickiness. Maybe some of the stickiness is from residual goo? Some products that carry "green" labels substitute common short-chained solvents, e.g., aldehydes or ketones, with long-chain, naturally occurring compounds of the same functional-group class. For example, a short chain ketone like acetone with a long-chain ketone. Those long-chain compounds may stick around for quite awhile. Imagine the difference between cleaning something with light mineral spirits versus kerosene.

    Heat may help them evaporate, but you may also effectively rinse them off using a short chain aliphatic hydrocarbon (e.g., VM&P naptha) in which it is miscible. That might get rid of the stickiness, but your plastic will still be ruined. Some OOPS formulations contain toluene or chlorotoluene. That will often cause crazing of polystyrene-like and acrylic plastics, as Kermit mentioned. So far as I know, there is nothing you can do about that either.

    When cleaning goo from something, I typically start with either light mineral spirits or VM&P naptha. If that doesn't work, I keep a can of the same stuff mixed with about 5 to 10% toluene (or xylene). That usually works. I never use acetone, MEK, or anything containing acetone or MEK on plastics, unless I am sure they are safe to use. Even pure mineral spirits will cause some haziness to polystyrene, such as CD cases. An alternative for such sensitive plastics is soft butter.

    John
     
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  4. wayneh

    Expert

    Sep 9, 2010
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    I've had various plastic things turn "sticky" even without any solvent contact. It's inexplicable but is definitely NOT something that can be wiped off - it's the plastic itself. You can mitigate it a little by sprinkling it with corn starch but that's probably not such a good idea near a hard drive. One item of mine - a barbecue tool - eventually lost its stickiness after several trips thru the dishwasher. Also not so useful for a hard drive. I frankly don't understand it.
     
  5. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    another great use for WD-40. cleaning plastics! never found a plastic it would destroy and it leaves a nice shiny finish when wiped with a dry cotton towel
     
  6. strantor

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    Oct 3, 2010
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    Paint it with clear acrylic. The paint should have no priblem sticking
     
  7. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Isopropanol is a great solvent because it does not dissolve/swell common polymers. Yet, it dissolves many other solvents quite well.

    Assuming you did not decompose the plastic but simply swelled the polymer. The swelling is essentially a solvent/solute situation. Good solvents swell and bad solvents do nothing. To remove the good solvent from the polymer, you need a new liquid that is a bad solvent for the polymer but a better solvent for your cleaner. Essentially a competitive extraction.

    I would recommend removing the hard disk from the case and soaking it in isopropanol (91%) for a day. After a day, dry it and it shouldn't be sticky.
     
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