Terpolymerization of ethene, acrylonitrile and vinyl acetate

The free‐radical terpolymerization of ethene, acrylonitrile and vinyl acetate was studied at 2000 bar in the temperature range from 170°C to 240°C in a continuously operated tubular‐type reactor. Polymerization was induced either thermally or chemically by di‐ tert ‐butyl peroxide as the initiator. Addition of vinyl acetate to ethene and acrylonitrile substantially enlarges the range for polymerization in the homogeneous fluid phase as compared to the binary copolymerization of ethene with acrylonitrile; a terpolymer with a high content of nitrile functional groups can be obtained from a single‐phase reaction. The six reactivity ratios of this terpolymerization, r EA , r EV , r AE , r AV , r VE and r VA are derived by applying first‐order Markov‐chain simulations. As ethene is the major component in the monomer mixtures, r EA and r EV are obtained with higher accuracy. For r EA the Arrhenius expression r EA = 2,6 · exp(−2,1 · 10 3 · ( T/K ) −1 ) is found (for 2000 bar). r EV = 0,9 ± 0,2 appears to be independent of temperature. The accuracy of the reactivity ratios r VE , r AV , r VA and r AE is not sufficient to detect a temperature dependence. The terpolymerization is also treated as a quasi binary copolymerization of ethene/vinyl acetate and acrylonitrile.