Application of ¹³C‐labelled initiators and ¹³C NMR to the study of the kinetics and efficiency of initiation of styrene polymerization

Kinetic modeling of free radical polymerization of styrene initiated by the bifunctional initiator 2,5-dimethyl-2,5-bis(2-ethyl hexanoyl peroxy)hexane

“…For AIBN, a theoretical value of M n is calculated from the initiator concentration and with f 1: The M n measured is superior to the prediction, which indicates an efficiency factor smaller than 1. If this difference is only due to the efficiency, the ratio of the two values gives the efficiency f 0:7 for the AIBN, which is close to the literature value [35]. For Lu256, one can observe that the measured molecular weights are close to the theoretical values at low temperatures and high initiator concentrations, which makes efficiency factor as close to 1 as possible.…”

Studies in free radical initiation

“…The active species, benzoyloxy and phenyl radicals are considered responsible for chain initiation and for the formation of a wide variety of by-products (Refs 13, 16). The rate at which polymer chains are initiated has been found to depend both on the rate at which active species are generated and on the rate at which competing reactions take place Furthermore, it has also been concluded that the ratio of phenyl to benzoyloxy radicals depends on the nature of the solvent (Refs.…”

Thermal decomposition of some azo initiators. Influence of chemical structure

“…The major product compounds of its thermal decomposition, inside the cage and without vinyl monomers, are 2,2,3,3-tetramethylsuccinonitrile (TMSN) and ketenimine (KI) 21,22) . The ketenimine form itself is thermally unstable and reverts to cyanopropyl radicals.…”

“…The kinetic parameters determined using this technique are based on the heat (DH) of decomposition, assuming that azo decomposition of azo initiators studied occurs in the same way as that of AIBN 21,22) . Therefore the kinetic parameters determined by this method correspond to the apparent kinetic parameters due to the presence of different products of azo decomposition and not only to N 2 elimination.…”