Polyacrylonitrile prepared in ethylene carbonate solution. I. Kinetics at low conversion

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Abstract
The kinetics of acrylonitrile polymerization initiated by azobisisobutyronitrile in ethylene carbonate solution were studied at 50 and 60°C. Under these conditions simple solution polymerization kinetics should apply. The initial rate of polymerization was determined by varying the amount of initiator and the monomer concentration. The reaction is found to be first‐order in monomer concentration and approximately 0.6‐order in initiator concentration. The free radical derived from ethylene carbonate (by abstraction of a proton by a growing chain) apparently can only react with a monomer to start another polymer chain. It does not enter into termination reactions. That is, the solvent acts only as a transfer agent and a diluent and does not affect the rate of polymerization by entering into other reactions. The transfer reactions are relatively unimportant (transfer to monomer is negligible: transfer to solvent is small) as indicated by a study of the degree of polymerization calculated from the intrinsic viscosity. Thus, quite high molecular weight polymer can be obtained. The reaction is first‐order to high conversion and is independent of the viscosity of the medium.