114687-22-8Relevant articles and documents
The influence of the polymer matrix on the reactions of the nitroxyl radical with aromatic amines
Griva, A. P.,Denisova, L. N.,Denisov, E. T.
, p. 1429 - 1432 (2007/10/02)
The kinetics of the reactions of 4-benzoyloxy-2,2,6,6-tetramethylpiperidin-1-yloxy radical () with six aromatic amines in benzene and polypropylene (PP) have been investigated.It has been established that the reactions proceed bimolecularly in the kinetic region.The rate constants and activation energies for the reactions, and the frequencies of the rotational and translational diffusion of the radical under the experimental conditions have been measured.It has been shown that, on passing from the solution to PP, the reaction rate constants diminish and the activation energies increase and that in PP the reactivities of the amines are levelled out.There is a correlation between the rate constants and the molecular mobilities in the PP - benzene system.The following rule has been established for the first time: the greater the volume of the reactant (the amine), the greater the difference between the rate constants and activation energies for the reaction in the liquid phase and in the polymer.These features of the reactions in the solid phase have been explained in terms of the concept of the "rigid cage".The energy barrier which must be overcome by the reactants in PP in order to assume orientations favourable for the reaction has been calculated from the experimental data ( Vor = 8.5 - 13.5 kJmol-1 ; 333 K ).It has been observed that Vor increases with increasing volume of the reactant.The Gibbs free energy necessary to rearrange the form of the PP cage when the reaction of the radical with an amine takes place in it has been determined ( 33 kJ mol-1).
