Process parameters branched-chain oxidation reaction

In Chapter 1 we briefly considered the critical phenomena in branching chain reactions consisting in the qualitative transfer from the slow mode of reaction to the intensive (self-accelerated) one at negligible changes in the parameters of a reaction system. Investigations of critical phenomena are still urgent. Increased interest in this problem is closely associated with the practical tasks of combustion, fire and explosion safety, inhibition of oxidation processes, etc. [1-3, 26-50],... 

The nonlinear processes of interaction of the chains determine the existence of two quasi-stationary modes of oxidation simple chain and steady-state branched-chain modes, with a difference in the rates of lO (Fig. 5.3) and a critical transition between them upon variation of the reaction parameters, especially, the pressure (Fig. 3.2). 

The degradation and combustion behavior of polycarbonate/POSS hybrid system has been reported recently.48 Different loading contents of trisilanolphenyl-POSS (TPOSS) were melt blended with polycarbonate matrix (PC). The data shown in Table 8.4 indicate that no improvement in thermal stability parameters (i.e., onset decomposition temperature and peak decomposition temperature) was observed compared to the neat polycarbonate. The thermo-oxidative degradation process of the hybrid system proved to be a complicated process, which includes hydrolysis/alcoholysis of the carbonate linkage, free radical oxidative chain degradation, reformation, and branching and cross-linking reactions. 

The model also revealed the importance of non-linear interactions of chains, which determine the existence of two quasi-stationary oxidation modes. The difference in reaction rate between them is about four orders of magnitude. A critical transition between these modes is taking place due to small changes in reaction parameters, e.g., pressure. This critical transition leads to a very fast increase in the oxidation rate and an abrupt transition from the low-pressure slow oxidation to the fast high-pressure stationary chain-branching process. In the latter mode, radical generation is no more determined by a slow initiation reaction, but by very fast chain-branching reactions. It is the phenomenon... 

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