The polymerization of acrylonitrile in aqueous solution. Part III. The ferric ion‐photosensitized reaction at 15, 25, 30, and 50°C.

Abstract

AbstractThe Fe3+OH− photosensitized polymerization of acrylonitrile in aqueous solution at 15, 25, and 35°C. has been studied dilatometrically. Reproducible steady rates Rp, aftereffect rates Rpae, and stable fine polymer suspensions are observed. By the methods of kinetic analysis given in Part II, the following parameters of the reactions of S*‐type polyacrylonitrile radicals have been determined: propagation, Ap = 3 × 107 l. mole−1 sec.−1, Ep = 4.1 kcal. mole−1; mutual termination, At = 3.3 × 1013 l. mole−1 sec.−1, Et = 5.4 kcal. mole−1; termination by Fe3+OH−, Atf = 6.7 × 105 l. mole−1 sec.−1, Etf = 2.3 kcal. mole−1. Above 40°C. the polymer suspension precipitates more rapidly, Rp is less reproducible, and rate constants for the aqueous phase reaction cannot be determined. A system which has been photopolymerized at 25°C. when heated to 50°C. shows a short burst of reaction followed by an aftereffect which is smaller and decays more slowly than that which the system would have had at 25°C.