  A simple dynamical system that models the competitive thermokinetics and
chemistry of cellulose decomposition is examined, with reference to evidence
from experimental studies indicating that char formation is a low activation
energy exothermal process and volatilization is a high activation energy
endothermal process. The thermohydrolysis chemistry at the core of the primary
competition is described. Essentially, the competition is between two
nucleophiles, a molecule of water and an -OH group on C_6 of an end glucosyl
cation, to form either a reducing chain fragment with the propensity to undergo
the bond-forming reactions that ultimately form char or a
levoglucosan-end-fragment that depolymerizes to volatile products. The results
of this analysis suggest that promotion of char formation under thermal stress
can actually increase the production of flammable volatiles. Thus we would like
to convey an important safety message in this paper: in some situations where
heat and mass transfer is restricted in cellulosic materials, such as
furnishings, insulation, and stockpiles, the use of char-promoting treatments
for fire retardation may have the effect of increasing the risk of flaming
combustion.
