Aspects of the mechanisms of smoke generation by burning materials

Abstract

This paper is concerned with the investigation of the detailed aspects of smoke generation during the burning of natural and synthetic solid materials under simulated fire conditions. With this objective in mind, the first portion of the paper is devoted to a review of relevant basic smoke formation studies. This review identifies the complex physical, chemical, and electrical processes that are believed to be important in smoke particulate production. The remainder of the paper presents measured experimental data and discusses observed trends in terms of many of the processes set forth in the previous section. The resulting increase in particle concentrations as heating rates are increased in nonflaming combustion is related to nucleation and condensation processes. Significant fundamental differences in smoke characteristics were observed between flaming and nonflaming conditions, and this is attributed to specific differences in controlling mechanisms and resulting pathways leading to particulate formation. Measured differences in smoke properties resulting from increased environmental temperature are similarly explained. The effects of polymer substrate properties and effects of various additives for a given substrate on observed smoke particulate properties are also discussed in terms of basic processes, although the determination of the actual mechanisms responsible for the observed smoke characteristics require further study. Finally, results of chemical analyses of smoke particulates from a variety of materials conducted as part of this study indicate that notable differences in particulate formation mechanisms are likely among the materials studied.