Char type, change

Figure 3. Coal series A and the change in char type with oxidation (373 K).

Solutions of these fire retardant formulations are impregnated into wood under fliU cell pressure treatment to obtain dry chemical retentions of 65 to 95 kg/m this type of treatment greatly reduces flame-spread and afterglow. These effects are the result of changed thermal decomposition reactions that favor production of carbon dioxide and water (vapor) as opposed to more flammable components (55). Char oxidation (glowing or smoldering) is also inhibited. 

The thermal decomposition of coal is a complex sequence of events (Stein, 1981 Solomon et al., 1992) (Chapters 13 and 16) that can be described in terms of several important physicochanical changes, such as the tendency of the coal to soften and flow when heated (Chapters 8 and 9) or the relationship to carbon type in the coal (Solomon, 1981). In fact, some coals become quite fluid at temperatures of the order of 400°C-500°C (750°F-930°F) and there is a considerable variation in the degree of maximum plasticity, the temperature of maximum plasticity, as well as the plasticity temperature range for various coals (Kirov and Stephens, 1967 Mochida et al., 1982 Royce et al., 1991). Indeed, significant changes also occur in the structure of the char during the various stages of devolatilization (Fletcher et al., 1992). 

All of the vibration types shown in Figure 16-2 may be possible in a molecule containing more ihan two atoms. In addition, interaction orcouplingof vibrations can occur if the vibrations involve bonds to a single central atom I he result of coupling is a change in the char-acterislics of the vibrations involved. 

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