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Thread: Expired Materials

  1. #1
    Join Date
    Aug 2018

    Expired Materials

    Can expired Materials cause preform to be whitish? How long can a Pet Resin material stay before its expiration?

  2. #2
    Join Date
    Aug 2014

    Re: Expired Materials

    "Expired" is probably a bad term to use. Plastic sitting over long periods of time can become oxidized. This is a form of degradation and it can cause all sorts of issues from discoloration, to processing issues, to failure in the field. Have a MFI done on the material and if your within 5% of what it should be then you should be ok from a structural/functional perspective. If the oxidation is causing the discoloration, there is nothing you can do about it that I am aware of so if the color is an issue then scrap it.

    Discoloration can also be caused by too hot of temps on your dryer (speeds up oxidization and degridation).


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