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Effect of Pigmentation in Particulate Formation from Fluoropolymer Thermodegradation in MicrogravityFires aboard spacecraft have occurred as a result of overheated electrical wires and thermodegradation of their insulation, which is composed of fluoropolymers. The particulate products of polymer thermodegradation are only 20-50 run in diameter and are thought to play a role in "polymer fume fever". Therefore an experimental study of the particulates produced by intense ohmic heating of various fluoropolymer-insulated 20 AWG copper wire (representative of spacecraft materials) was undertaken in normal gravity and in microgravity. The 2.2 s drop facility at NASA LeRC and 1.5 s drop facility at the Colorado School of Mines were used to achieve low gravity conditions. Thermophoretic sampling was used for particulate collection. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) were used to characterize the smoke particulates. It was found that the color of PTFE (Polytetrafluoroethylene) insulation has an overwhelming effect on the size, shape, morphology and, composition of the particulates. Size distributions and shape analyses using computerized image analysis showed that particle size distributions were also dependent on the pigment of the fluoropolymer insulation. The influence of pigment was observed in experiments under both normal and microgravity. Under microgravity conditions, owing to the lack of natural convective transport of particulates, much more particle aggregation was observed, and the nature of the aggregates was dependent on the color of the insulation.
Document ID
20000030723
Acquisition Source
Legacy CDMS
Document Type
Preprint (Draft being sent to journal)
Authors
Srivastava, Rajiv
(Colorado School of Mines Golden, CO United States)
McKinnon, J. Thomas
(Colorado School of Mines Golden, CO United States)
Todd, Paul
(Colorado Univ. Boulder, CO United States)
Date Acquired
September 7, 2013
Publication Date
September 1, 1998
Subject Category
Nonmetallic Materials
Report/Patent Number
AIAA Paper 98-0814
Funding Number(s)
PROJECT: RTOP 101-12-OA
CONTRACT_GRANT: NAG3-1685
Distribution Limits
Public
Copyright
Other

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