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Heating plastic

  1. Sep 22, 2016 #1
    Hi everybody!
    I was wondering, what substances do form when plastic is heated? I found on the internet that if plastic is heated in the oven (not microwave) at 325°C, it shrinks and become more thick, and it can be used for art work. I tried to search about it, but I found different opinions about it and I don't know the scientific answer. Does it liberate toxic fumes? If yes, does it do it at what temperature? What if I color it with acrylic colors before putting it in the oven, is it even worse?
  2. jcsd
  3. Sep 22, 2016 #2


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    Staff: Mentor

    There is no single answer, as there is no single "plastic". Decomposition products depend on the identity of the polymer heated, they can be relatively harmless or highly toxic. It can also depend on the temperature of heating.
  4. Sep 22, 2016 #3
    In this case I'll try to reverse the question, do you know a specific type that can be heated without toxic fumes? For example, the plastic of CDs is ok?
  5. Sep 25, 2016 #4
    I often recycle HDPE for mechanical parts:


    My main source of HDPE are milk bottles. I shred them using an old blender, then heat them up in the oven at 230-250°C until they are soft. No obnoxious gasses are emitted, but make sure you don't go higher in temperature or it may start decomposing or burning. Then I put the paste into a mould (usually made of wood), apply pressure with a few clamps and let it cool off. Once cold, it is a very hard material, easily machinable.
  6. Sep 28, 2016 #5
    Interesting... I'll try to search this material. Thank you both!
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