STABILIZATION AND MODIFICATION OF CELLULOSE DIACETATE - Photochemical Reactions in Heterochain Polymers - page 73

Expected stationary state may be good approximation for calculation of kinetics of
reaction flow. Mechanism of inhibition by azomethine conjugated compounds is
accompanied by the break of multiple carbon-nitrogen bond and addition of radical. In the
case of low-molecular azomethines separation of hydrogen atom and addition of radical to α -
carbon atom take place:
Р * + С=N → РН + С-N * -
Disappearance of conjugated bonds in the process of radical reaction was proved by data
of infrared-spectra. Inhibition by end primary NH 2 - groups proceeds with hydrogen atom
breaking off:
P * + RNH 2 → PH + RN * H
However, one should take into consideration that fact, that atomic radicals, being formed,
especially of tertiary atom, may take part in the chain transmission onto monomer [178].
Kinetic dependences of the rate of inhibited radical polymerization of styrene in the presence
of XXXV, XXXVI, XXXVII (Figure 2.17 - 2.19) show that the rate of polymerization
reaction decreases with the increase of azomethines concentration and depends on structure,
structural features and efficiency of the chain of PAC conjugation.
Figure 2.17. Dependence of /V/ styrene on temperature and structure of oligomer: 1 - without additives;
2 - 5 - with the addition of 0,0005 mole/l oligomer: 2 - XXXIII 3 - XXXV 4 - XXXVI 5 - XXXVII.