1. Processes involved

Figure 1 shows the main processes involved in the combustion of a plastic material. Each process identified in the first column is described from a physico-chemical point of view in the second. The third column groups together the important parameters, while the fourth mentions the characteristic quantities.

For simplicity's sake, we'll describe the situation of an object subjected to heat flux from another focus. Under the action of the incident flow, the material will heat up, essentially by conduction of heat from the exposed surface. Above a critical surface temperature, thermal degradation of the material gives rise to a gaseous phase. The mixing of pyrolysis gases with air leads to the formation of a flammable gas phase. Ignition can be caused...