Showing papers by "Gérard Riess published in 1965"

Contribution à l'etude de la cinétique de formation de polymères séquencés par voie radicalaire

Abstract: In order to study some aspects of radical polymerization initiated by a polymer, hexanediol sebacates in different degrees of polymerization were prepared. The endgroup was the tert-butyl perester which was used to polymerize the styrene. With such compounds, it is easy after the polymerization to take off the polyester backbone by hydrolysis. One can then study the mixture of polystyrene sequences and homopolystyrene made at the same time. It appears that if the speed of thermal decomposition of the tert-butyl perester group on the polyester is of the same order as that of the tert-butyl perbenzoate, the efficiency factor, i.e., the fraction of free radicals which effectively initiates the polymerization, is much smaller with a polymeric initiator. Moreover, the average degree of polymerization is much smaller in this case (even in the presence of a nonperoxidized polyester). It is believed that these two results can be explained by assuming each polyester backbone to act as a cage for the free radicals produced by its own perester group which aids their recombination and intramolecular transfer.