Monomer apparent reactivity ratios for acrylonitrile/ammonium itaconate radical copolymerization systems

Abstract

AbstractAmmonium itaconate was first used to copolymerize with acrylonitrile. This was achieved by using azobisisobutyronitrile as the initiator and dimethyl sulfoxide as the solvent. Effects of copolymerization systems on monomer apparent reactivity ratios for acrylonitrile/ammonium itaconate copolymers were studied. The values of monomer apparent reactivity ratios were calculated by Kelen‐Tudos method. The apparent reactivity ratios in the aqueous suspension polymerization system are similar to those in the solution polymerization system at polymerization conversions of less than 18% [reactivity ratio of acrylonitrile (rAN) = 0.47 ± 0.01, reactivity ratio of ammonium itaconate (rAIA) = 3.08 ± 0.01]. At conversions of more than 50%, the changes of monomer apparent reactivity ratios become less prominent (rAN = 0.68 ± 0.01, rAIA = 2.47 ± 0.01). In water‐rich reaction medium [(H2O/dimethylsulfoxide (DMSO) > 80/20)], the monomer apparent reactivity ratios are approximately equivalent to those in the aqueous suspension polymerization system. In DMSO‐rich reaction medium (DMSO/H2O > 80/20), the apparent reactivity ratios are similar to those in the solution polymerization system. With an increase in the polarity of the solvent, the values of apparent reaction ratios both decrease. The values of apparent reaction ratios gradually tend to 1 with increasing the copolymerization temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3920–3923, 2007