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From: wmartin@brl-tgr.ARPA (Will Martin )
Newsgroups: net.consumers,net.misc
Subject: Lifetime of foam products
Message-ID: <5783@brl-tgr.ARPA>
Date: Wed, 14-Nov-84 17:46:31 EST
Article-I.D.: brl-tgr.5783
Posted: Wed Nov 14 17:46:31 1984
Date-Received: Sat, 17-Nov-84 04:24:42 EST
Distribution: net
Organization: Ballistic Research Lab
Lines: 24

Lately, I have noticed various plastic foam pieces deteriorating or
disintegrating. This reminded me that I had also seen such an effect
in the past; the classic example is the foam mat on the old AR turntable.
I have even seen references in print to the effect that those foam mats
all disintegrated. I've seen foam pieces in such places as the battery
compartment of a portable radio just turn to crumbles. 

Does anyone know what is going on here? I don't know what type of plastic
these foams are made from; could some chemist on the net discuss this?
Does this stuff have an actual "lifetime", and it will disintegrate after
"n" years from being formed, no matter how carefully it is treated or stored?
Or is this due to environmental effects, like temperature changes and 
airborne contaminants? 

I'm worried that many consumer products have pieces of foam built in as
cushioning or to take advantage of the foam's springiness, like on
a battery-compartment door. Were all these uses of foam done with no
knowledge of the fact that the foam will deteriorate? Or will some last
much longer than other types? How can we determine what type we have,
and what should be used to replace it?

Will Martin

USENET: seismo!brl-bmd!wmartin     or   ARPA/MILNET: wmartin@almsa-1.ARPA