From: firstname.lastname@example.org (Bob Wilson)
Subject: Re: Difference between EPDM and nitrile
Date: Fri, 27 Sep 2002 03:24:27 -0000
Organization: Your Organization
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In article <3D8FDF2F.B7C3603B@alphalink.com.au>, email@example.com
>> Hi All
>> I`m trying to find the differences in EPDM (Ethylene Propylene Diene
>> Monomer) and Nitrile (Buna-N, NBR). Can one replace another?
>> Any help would be appreciated.
>I presume you mean artificial rubber compounds ?
>If so then each manufacturer will have different blends/formulations
>depending on application.
>Asking the question in Sci.chem or sci.polymers will get a better
>Organic chemistry isn't my strong suit!
Nitrile rubber is also known as "Butyl Rubber" or "Buna-N". It is the stuff
that "normal" O-rings are made of. It has relatively good resistance to oils
and non-aromatic hydrocarbons (e.g. gasoline, diesel and so on). It is not
good at low temperatures, since it becomes very stiff and loses its ability
to flex. Butyl rubber has poor resistance to UV and exposure to aromatic
hydrocarbons (toluene, xylene, benzene etc) will cause very significant
EDPM's main claim to fame is excellent resistance to ozone, and UV. It has
poor resistance to oils, and to both non-aromatic and aromatic hydrocarbons.
It has excellent dielectric strength. EDPM also has better resistance to
mechanical comperssion "set" than butyl rubber, and it remains more flexible
at low temperatures.
So it depends on what you want in properties. For many uses, EDPM is an
*unsatisfactory* substitute for butyl rubber. For example, if you relaced
the o-rings in your car (which are largely butyl) with EDPM O-rings, you
would have a lot of oil and gas on your driveway!