Cyclopolymerization. II. Kinetics of polymerization of acrylic anhydride

The kinetics of polymerization of acrylic anhydride has been studied at 34.6°C. in bulk and in solution in cyclohexanone and in dimethylformamide. The order of reaction with respect to the initiator concentration (azobisisobutyronitrile) varies from 0.67 to 1. The rate of reaction is high; it remains practically constant over a range of monomer concentration from 0.76 to 4.29 mole l.−1; at higher concentrations, it increases linearly with the molar concentration. The results have been interpreted on the basis of a progressive insolubilization of the polymer molecules on account of residual double bonds, and on the basis of the occlusion of growing chain radicals. The presence of trapped radicals was demonstrated by EPR measurements. Their concentration was evaluated by comparison with the spectrum of DPPH; it increases with the time, and with the polymerization temperature. After 8 hr. polymerization at 60°C. it is equal to 5 × 10−4 mole l.−1.