Experimental investigation into mechanical destruction of intumescent chars

It has been shown that the fire protection properties of intumescent coatings depend on the heat protection of the char layer. This, in turn, depends on the char cap height, its structure, etc. One of the most important problems is to analyze processes of char mechanical destruction. It is obvious that even if char has excellent heat-shielding properties, but at the same time is easily destructible by mechanical action, the whole fire protection will be weak. This paper presents a broad discussion on the problem of mechanical destruction of intumescent chars in the application to fire protection of buildings in conditions of fires and protection of rocket engines in conditions of intensive mass and heat flows. Data on mechanical strength of various types of chars in hot and cold states are presented and discussed. Various methods are compared. The rheological approach to destruction is concerned. Some aspects of destruction behavior observed previously are explained. (Example materials include EPDM elastomers and phenolic resins with and without flame retarding additives.)