Polystyrene

Jim Lindner <vidipax<-a t->panix< . >com> writes

>I would appreciate hearing any information about the longevity
>issues associated with polystyrene and styrenes in general.
>... Also,
>is anyone having problems with polystyrene enclosures over
>time--particularly cases used to house CD's?

I have been working with longevity of CD's for some time now, and
have had the same questions about the jewel cases for CD's. This is
what I came up to in assistance with Mads Chr. Christensen from the
School of Conservation in Copenhagen:

Polystyrene (PS) consist of a long carbon chain, with a aromatic
hydrocarbon linked to every second carbon atom. So the chemical
structure is quite simple.

What there can be the dark horse is remains of monomers, that didn't
polymerize. I am unaware what kind of damage they can cause, but
suppose that this is only relevant when discussing PS-foam
(flaminco-plates) and not clear PS.

Polystyrene has been used as plastics since 1947. I have seen PS
from the about 1955 in quite good shape, though yellowing.

Clear polystyrenes (PS) does not contain plasticizers. This is
good!-)

PS are regarded as safe for storage of photographic materials, as
far as I know. (And photographic Conservators are quite strict).

PS is most vulnerable towards photo-oxidation successed??? by thermal
degradation. Ozone, hydrolysis and biodegradation is no problem.(3)

All in all:  PS is OK for storage of CD's. If some one disagree,
please let me know.

Bibliography:

    1.  John S Mills & Raymond White
        The organic chemistry of Museum Objects, 2nd ed.
        Butterworth-Heinemann, Oxford 1994

    2.  John Morgan
        Conservation of Plastics
        Museum & Galleries Commission
        London, 1991

    3.  N.S. Allen, M. Edge & C.V. Horie ed.
        Polymers in Conservation
        Royal Society of Chemistry
        London 1992

Jacob Trock
Dronningensgade 52
DK - 5000 Odense C
Denmark
ph./fax. +45 66118816

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                  Conservation DistList Instance 11:2
                   Distributed: Friday, June 20, 1997
                        Message Id: cdl-11-2-003
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