Re: Suitable capacitor dialectrics

["David Huffman" <huffman-at-fnal.gov> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

I have a large roll of polystyrene waiting to be constructed into a cap,
however my schedule presently does not allow it to happen. I only have it
because the price was right (free). I believe I will place a piece in some
transformer oil to see if anything nasty happens. I can do that and leave it
in the oil for quite a long time. I certainly know polystyrene is easily
dissolved by common solvents.
I would probably construct a flat capacitor so as not to cause physical
stress on the plastic. Probably should check the stuff in the exact oil used
for construction.
Dave Huffman
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, August 15, 2000 9:14 AM
Subject: Re: Suitable capacitor dialectrics


> Original poster: "Bert Hickman" <bert.hickman-at-aquila-dot-com>
>
> Tesla list wrote:
> >
> > Original poster: "Metlicka Marc" <mystuffs-at-orwell-dot-net>
> >
> > hello bert,
> > i was wondering what exactly happens to polystyrene in oil? i've had the
> > cup cap soaking for some time now and checked it after your post, it
> > doesn't seem mushy or anything?
> > marc
>
> Marc,
>
> Well, my notes indicated that (supposedly!) polystyrene either degraded
> or dissolved in mineral oil, and that it had poor chemical resistance.
> Unfortunately, my notes do not indicate the original source of the
> information, - I suspect it may have come out of one of the many books
> on plastics I rented from the local library a couple of years back.
>
> However, after seeing your post, I did a bit more digging and found that
> other (web-based) polymers references seem to indicate that polystyrene
> suffers no damage after 30 days immersion and that it has excellent
> resistance/no attack by mineral oils (as long as they have no aromatic
> or alaphatic solvent content). However, polystyrene is significantly
> more brittle than polyethylene or polypropylene, and may be more prone
> to cracking under applied stress.
>
> Your mileage may vary, but if your cup caps seem to be working OK, go
> for it! :^)
>
> -- Bert --
> --
> Bert Hickman
> Stoneridge Engineering
> Email:    bert.hickman-at-aquila-dot-com
> Web Site: http://www.teslamania-dot-com
>
>
>
>
>