Char Enhancing Approaches to Polymer Flammability: The Effect of Radicals on Magic Angle Spinning 13C NMR of Chars.

Published

October 28, 1996

Author(s)

Jeffrey W. Gilman, Takashi Kashiwagi, David L. VanderHart, S M. Lomakin, V Nagy

Abstract

Additives that increase the amount of charcoal-like residue or carbonaceous char that forms during polymer combustion are very effective fire retardants. However, very little is understood about the detailed struture of char or how it forms. Our research efforts focus on reducing polymer flammability by promoting char formation. Char formation reduces the amount of small volatile polymer pyrolysis fragments, or fuel, available for burning in the gas phase; this in turn reduces the amount of heat released and feedback to the polymer surface. The char also insulates the underlying polymer, due to its low thermal conductivity, and reradiates externally impinging energy away from the polymer. The char must also function as a mass transport barrier, by physically delaying the volatilization of decomposition products and or trapping decomposition products through chemical reaction. The physical structure of the char is important in this role. Foamy char structure appears to be more fire resistant than brittle, thin char. This char enhancing approach is most successful when the polymer chars rapidly and early in the burning process. To be useful the charring process must occur at a temperature above the processing temperature but below the temperature where rapid gasification of the polymer to combustible fuel occurs.

Proceedings Title

National Institute of Standards and Technology. Annual Conference on Fire Research: Book of Abstracts

Conference Dates

October 28-31, 1996

Conference Location

Gaithersburg, MD

Pub Type

Conferences

Download Paper

Local Download

Keywords

fire research, fire science, char, flammability, char formation, additives, thermal conductivity, radicals

Citation

Gilman, J. , Kashiwagi, T. , VanderHart, D. , Lomakin, S. and Nagy, V. (1996), Char Enhancing Approaches to Polymer Flammability: The Effect of Radicals on Magic Angle Spinning 13C NMR of Chars., National Institute of Standards and Technology. Annual Conference on Fire Research: Book of Abstracts, Gaithersburg, MD, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=916904 (Accessed April 25, 2024)