Abstract
The processes taking place in the preflame zone at flame spread over the surface of epoxy polymer have been investigated in the present work. It has been shown that heating of yet unignited polymer ahead offlame spreading over the thermally thick samples is done mainly by the heat conduction through condensedphase. The compositions of highly- and hardly-volatile products of gasification are determined in conditionsof the preflame zone. It is shown that the main combustible product of gasification is CO (ca. 85 %). The mass rates of gasification and the linear velocities of an injection of gasification products into gas phase of preflame zone have been determined. The complicated aerodynamic structure of the preflame zone with avortex formation is shown to exist. As a result oxygen gets a free access to a polymer surface and can participate in gasification processes. Experimental simulation of the epoxy polymer gasification processeswas carried out in the oxygen-18 enriched atmosphere. The main oxygen-containing product of gasificationis shown to be generated both as a result of pyrolysis, and a result of thermooxidation. More than 75% ofcarbon dioxide is formed only due to thermooxidative destruction, and 75 - 90% of carbon oxide is formedonly due to pyrolysis. It has been shown that in a course of epoxy polymer gasification in preflame zone themain mass of combustible products is generated by pyrolysis, but an energy for this is mostly supplied by simultaneously occurred exothermal processes of thermooxidation of the near-surface layers of epoxy polymer.