Determination of monomer apparent reactivity ratios for acrylonitrile-acrylamide copolymerization system

Effect of copolymerization systems on monomer apparent reactivity ratios for copolymer of acrylonitrile with acrylamide was studied for contrast. Values of monomer apparent reactivity ratios were calculated by Kelen-Tudos method. It has been found that the apparent reactivity ratios in aqueous suspension polymerization system were similar to those in solution polymerization system at polymerization conversion less than 18% [reactivity ratio of acrylonitrile (rAN) = 0.398 ± 0.004, reactivity ratio of acrylamide (rAM) = 2.61 ± 0.02]. As conversion of more than 60%, the changes of monomer apparent reactivity ratios become less prominent (rAN = 0.651 ± 0.008, rAM = 1.98 ± 0.01). In water-rich reaction medium [(H2O/dimethylsulfoxide (DMSO) > 80/20), monomer apparent reactivity ratios were approximately equivalent to those in aqueous suspension polymerization system. In DMSO-rich reaction medium (DMSO/H2O > 80/20), apparent reactivity ratios were similar to those in solution polymerization system. With an increase of polarity of solvent, values of apparent reaction ratios both decreased. The values of apparent reaction ratios gradually tend to 1 with increasing the copolymerization temperature. C 2005 Springer Science + Business Media, Inc.