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Dichloromethane + Polycarbonate

  1. May 18, 2010 #1
    First off I will say that chemistry is not my field of expertise so bear with me.

    I am using dichloromethane to weld polycarbonate components together. We are trying to come up with a solution to un-weld the components when necessary. That said, by instruction, I am to completely understand the chemical reaction between this solvent and the component material.

    What I do understand is that the resulting weld is purely polycarbonate. This is required since out-gassing of any other type of material is not desired (adhesives are out of the question).

    I have searched numerous technical databases for an explanation of this reaction but have come up with virtually nothing. I was wondering if someone could point me in the direction of the information I am seeking or some sort of primer that explains how the reaction takes place.

    Thank You!
     
  2. jcsd
  3. May 19, 2010 #2

    chemisttree

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    DCM dissolves the polycarbonate which produces a thick polycarbonate adhesive fluid containing DCM. The weld must dry to be made fast and once dried won't easily be unwelded if that is possible at all.

    The method is also prone to solvent crazing from the solvent. So, no chemical reaction here, just dissolution followed by drying of the solvated plastic.
     
  4. May 19, 2010 #3
    What exactly is solvent crazing?
     
  5. May 19, 2010 #4

    chemisttree

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    Solvent crazing is the rearrangement of the amorphous polymer into a more crystalline one. Any stress thereafter causes multiple cracks to form along the direction of the stress. These multiple small cracks are known as 'crazing'. In the lab I have seen polypropylene wash bottles containing acetone shatter when this solvent induced recrystallization gets bad enough. It takes years to occur but it is a bit of a shocker when you pick up a plastic solvent bottle and it shatters in your hand!
     
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