non-permeable plastic
Postma
L.S.
Who can provide info on plastics that have an extreme low moist permeability.
The plastic I am looking for has to protect electronics for 10 years in a submersed
environment (up to 10 years).
I do not want to use glass or metal in this particular occasion. Which plastic is
the closest to these alternatives.
By the way, it preferably should also be easily processable (injection moulding).
Looking very much forward to any suggestion.
Kind regards
Epi Postma (Holland)
Brent Viers
Poly(vinyl alcohol) or it's copolymer ethylene vinyl alcohol is used in the
food packaging biz for its barrier properties. I am not aware of any
electronics usage-but its dielectric constant should be that of most organics.
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Michal Tencer
In article <323DB4...@pop.pi.net>, Postma <epi...@pop.pi.net> says:
>Who can provide info on plastics that have an extreme low moist
permeability.
>The plastic I am looking for has to protect electronics for 10 years in a
submersed
>environment (up to 10 years).
>I do not want to use glass or metal in this particular occasion. Which
plastic is
>the closest to these alternatives.
>By the way, it preferably should also be easily processable (injection
moulding).
I am afraid you will not find any plastic like that. All polymers are
water penetrable to a certain extent.
The protection polymeric materials give to electronics in direct contact
with it is not aa a barier but through good adhesion (possibly chemical)
which will make formation of a water layer impossible thus inhibiting any
corrosion processes.[It does provide some moisture averaging effect]
If you are looking at plastic containers for electronics, some materials
in limited amounts and cerain geometries could achieve your goal of 10
years with help of a desiccant.
M.T.
Roger W. Faulkner
Postma wrote:
> Who can provide info on plastics that have an extreme low moist permeability.
> The plastic I am looking for has to protect electronics for 10 years in a submersed
> environment (up to 10 years).
> I do not want to use glass or metal in this particular occasion. Which plastic is
> the closest to these alternatives.
> By the way, it preferably should also be easily processable (injection moulding).
I agree with another poster regarding the desirability of a desicant.
One option is to have a multilayer structure with a desicant in the
lower layer. Among the common plastics, I'd pick polyphenylene sulfide
(Riton) for this application. If a more exotic/expensive polymer can be
used, try Halon (polychlorofluoroetylene, or so).
...Roger Faulkner
Roger W. Faulkner
Reposting article removed by rogue canceller.
Christopher Dobbin
In article <51l4bq$o...@news.ececs.uc.edu>,
Brent Viers <br...@jemcom.crs.uc.edu> wrote:
>Poly(vinyl alcohol) or it's copolymer ethylene vinyl alcohol is used in the
>food packaging biz for its barrier properties. I am not aware of any
>electronics usage-but its dielectric constant should be that of most
organics.
Sorry, but PVA and EVOH are used in food packaging as OXYGEN
barriers! They are highly hygroscopic and
moisture kills the barrier properties. For this
reason, they are always sandwiched with a moisture
barrier polymer such as (gasp) good old polyethylene.
For reference, high density polyethylenes have excellent
moisture barrier properties and can be readily injection
molded. They are chemically inert and have a very low
dielectric. If more flexibility is required, the LLDPE and LDPE variants
can also be used.
""""""""""""""""""""""""""
Chris Dobbin
Curt Peterson
You might want to look at Liquid Crystal Polymers ( LCP's ) for
moisture barrier. Regards, Curt Peterson