| Popis: |
The kinetics of polymerization of acrylonitrile (AN) initiated by the systems V(IV)/N-bromosuccinimide (NBS) and V(HI)/NBS have been investigated in aqueous acid media in the 25–35°C range. Evidence for Michaelis-Menten kinetics is obtained from oxidation data with the system V(IV)/NBS. Rates of polymerization varied as [AN]3/2, [NBS]½, and [Vn+]½, where n = 3 or 4. The retardation of oxidation as well as polymerization by increasing [H+] results from protonation of NBS which inhibits complexation. A mechanism involving formation of a complex between the reductant metal ion and oxidant followed by its reaction with AN to generate initiating radicals, coupled with mutual termination of growing radicals, accounts for the kinetics of polymerization. |
