Hi folks:

     Before getting started I want to say that references to Kapton should
not be taken to necessarily indicate a specific reference to Du Pont's brand
of polyimide.

     I have not read all of the postings on this subject but the few I have
read did not mention the problem of arc-tracking that causes Kapton to
become self-sustaining for combustion.

     My first encounter with Kapton's ability to burn when heated
electrically was during ground operations related to preparing the Magellan
(also know as Venus Radar Mapper) satellite at Martin Marietta in Denver.
One of our technicians tried to blind-mate a connector but didn't get the
clocking right.  As I recall (from around 1991) contact was made between a
hot battery pin and a ground pin.  The Kapton caught fire.  It wasn't too
long after this that NASA released a video showing how dramatic the
combustion event could be, and how flame propagation continued after power
was turned off.

     I think that the problem has to do with the chemistry of the pyrolysis
event peculiar to Kapton.  I'm not sure I can accurately describe the
sequence of events but I seem to recall that as the molecule breaks apart it
leaves conductive carbon tracts that assist in the heating and decompostion
of further material.

     A few months ago 60 Minutes (or it might have been 20 20 or similar
news show) put forth the Kapton self-sustaining combustion theory for the
crash in Nova Scotia.

     Radiation cross-linked Tefzel (ETFE) wire insulation is the current
favorite here.

Pat Hogue
Materials and Processes Engineering
Honeywell Satellite Systems Operation
Glendale, AZ 85308
(602) 561-3748

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