Radical polymerization of vinyl acetate with primary radical termination

Vinyl acetate was polymerized at high initiation rate with 2,2′-azobis(2,4-dimethyl valeronitrile) as initiator at 50°C. In this polymerization, the power dependence of polymerization rate on the initiation rate is smaller than at lower concentration of monomer. This dependence was kinetically analyzed at each given concentration of monomer. Average degree of polymerization of polymer formed depends on the concentration of initiator. This dependence was explained by considering chain and primary radical terminations and transfer to monomer of polymer radical, and the initiator efficiency (=0.503) was deduced. It was found that the chain termination is inversely proportional to solvent viscosity, but the primary radical termination is not inversely proportional to solvent viscosity. Further, the value of the primary radical termination rate constant (=1.4 × 10⁹l./mole-sec) was estimated.