Marv Gozum @ JHN
marvin.gozum at jefferson.edu
Thu Apr 28 19:04:02 UTC 2011
Thanks Chuck, that's very informative. That pretty much describes
the life cycle of a lot of old plastic I've encountered.
You say evaporate, is possible then to seal plastic parts to prevent
plasticizer migration, and prolong the parts life, even if its
already old but still has not fallen apart? Add any kind of
plasticizer to revitalize old plastic?
Yes, vinyl binders seem to almost weep something, that doesn't seem
good! I see Bakelite endures over time, but it very ceramic like and
tends to cracks if dropped.
Sorry all, at most this should be discussed at the HP forum group, so
this is my last topic digression on the volt-nuts forum.
At 10:36 AM 4/28/2011, Chuck Harris wrote:
>The only real way to tell with plastics is to subject them to the test
>of time and environment. The basic problem is one of plasticizer migration.
>Many plastics have an added goo that improves the way they flow in molding,
>and softens the plastic so that it is suitable for use. The plasticizer
>evaporates slowly out of the plastic making it shrink, and leaving it very
>brittle. Some plasticizers migrate to the surface leaving the plastic very
>sticky... vinyl (PVC), particularly soft vinyl, which is heavy in plasticizer,
>has that problem. That plasticizer migration is what makes xerox'd pages
>stick to vinyl binders, leaving the lettering behind on the vinyl...
>Some of the ancient plastics aren't really plastic at all... bakelite is an
>example.... and they hold up incredibly well. The common characteristic,
>in my opinion, no plasticizer. The much fabled BPA is one of the plasticizers
>that causes problems if it isn't used just right.... It also causes breast
>development in men, but that is another story.
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