Alternating copolymerization of ethylene with maleic anhydride

Abstract

Abstract The copolymerization of ethylene with maleic anhydride was carried out with γ‐radiation and a radical initiator, i.e., 2,2′‐azobisisobutyronitrile and diisopropyl peroxydicarbonate under pressure at various reaction conditions. The homopolymerization of neither monomer was observed in this system. In the γ‐ray‐initiated copolymerization the G value (polymerized monomer molecules per 100 e.v.) was shown to be between 10 3 and 10 4 . It was found that the dose rate exponent of the rate is approximately unity, and the rate is proportional to the amount of ethylene monomer. Apparent activation energies of 1.8 and 27.5 kcal./mole were obtained for γ‐ray‐initiated and AIBN‐initiated copolymerization, respectively. Since the composition of copolymer is independent of monomer molar ratio and the molar ratio of ethylene to maleic anhydride in the polymer is approximately unity, the monomer reactivity ratios were obtained as r E ≃ 0 and r M ≃ 0 for γ‐ray‐initiated polymerization at 40°C. Alternating copolymerization was, therefore, concluded to occur. Infrared analysis of the copolymer is almost consistent with this. The copolymer in the solid state is amorphous. It is soluble in water, cyclohexane, and dimethylformamide and insoluble in lower alcohols, ether, and aromatic hydrocarbons. The aqueous solution of polymer gave a strong acid.