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Re: Polypropylene (fwd)
---------- Forwarded message ----------
Date: Thu, 23 Jul 1998 23:33:19 -0500
From: Bert Hickman <bert.hickman-at-aquila-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Polypropylene (fwd)
Tesla List wrote:
>
> ---------- Forwarded message ----------
> Date: Thu, 23 Jul 1998 16:24:08 +-100
> From: "Gregory R. Hunter" <ghunter-at-enterprise-dot-net>
> To: 'Tesla List' <tesla-at-pupman-dot-com>
> Subject: Polypropylene
>
> Can anybody give me data on polypropylene film? I saw a flat plate cap at
> the UK Teslathon that appeared to be made of plastic document protectors &
> foil. I found some pocket-style document protectors at work and examined
> them. The recycling symbol says they are polypropylene. I can't find any
> values as to dielectric strength, dielectric constant, etc., in my
> literature.
>
> Also, does anyone know the meanings of the various plastics recycling
> symbols? For example, I know "HDPE 2" is polyethylene, but I'm wondering
> what the shorthand is for various other plastics.
>
> Cheers,
>
> Greg
Greg,
For the most part polypropylene (PP) and polyethylene (PE) have very
similar properties. PP tends to be a bit "stiffer", which can be a
problem with rolled caps using thicker sheets. While the actual
dielectric constant is around 2.2 - 2.3, the "practical" value for
homemade capacitor calculations is about 2.0 due to unavoiable space
between the plates and the dielectric material. Dielectric strength is a
function of the thickness of the material - use multiple thicknesses of
thinner material for best results.
Re: Shorthand Notation:
Recycling
Number Shorthand Material
#1 PET PolyEthylene Terephthalate
#2 HDPE High Density PolyEthylene
#3 PVC PolyVinyl Chloride
#4 LDPE Low Density PolyEthylene
#5 PP PolyPropylene
#6 PS PolyStyrene
#7 Other...
-- Bert --