The conventional "ignition" region emerges at temperatures higher than 880 K; the corresponding exothermal
activity practically ceases at extremely fuel-rich conditions ([Y.sub.fuel] > 0.3).This "quenching" behaviour is attributed to the significant reduction of essential radical species concentrations observed at high temperatures ([T.sub.in] > 900K) and fuel-rich mixtures; in fact, predictions of H and OH radicals concentrations are decreased by almost 5 orders of magnitude, when the inlet fuel concentration is quintupled, from a near stoichiometric value ([Y.sub.fuel] = 0.06, [lambda] = 1.04) to significantly fuel-rich conditions ([Y.sub.fuel] = 0.3, [lambda] = 0.16).
Thus, although the DSC heating thermograms of the PLA did not show melting endothermal peak, its DSC cooling thermograms displayed a broad weak melting exothermal
peak in the temperature range of 105-45 [degrees]C (Figure 1(b)).
The third exothermal
effect--and at the same time the stage of pyrolysis--took place when the temperature exceeded 361.2[degrees]C and was over at approximately 710[degrees]C.
Reduction of Fe2[O.sub.3] with aluminium (3) and magnesium (4) creates an additional exothermal
effect of the process:
The reader should note that the kinetic model is used not only to calculate the heat released by the exothermal
polymerization reaction, but also to deduce the evolution of the extent of reaction calculated from the simulated curing temperature.
One may see from the Figure that in the process of heating exothermal
phase transformations occur in the foils.
As can be seen, the liquid temperature rises sharply (less sharply so for R-600a) as a result of latent heat release (exothermal
absorption) during the first minute or so, but, eventually, as absorption ceases, the system regains thermodynamic equilibrium with the surroundings (see Figure 11).
This fine dust will react again with oxygen in an exothermal
This control strategy is termed auto-refrigerated reactor, largely utilized for a great variety of exothermal
reactions, including polymerization (Luyben, 1966, 1972, 1999; Henderson, 1987; Henderson and Cornejo, 1989; Toledo, 1992; Vasco de Toledo et al., 2000).
It is known that the urethane formation reaction proceeds with an exothermal
effect of 83.2 kJ/mol, but the isocyanate groups cyclotrimerization reaction with 66.5 kJ/mol .
In addition to these exothermal
products, a separate line of endo-thermal blowing agents is available.
TAC melts at 27[degrees]C and has an SADT of 89[degrees]C; exothermal
auto-polymerization may occur from 160[degrees]C.