Liquid carbon dioxide as a solvent for the radiation polymerization of ethylene

Abstract

Abstract The usefulness of liquid carbon dioxide as a solvent for polymerization of ethylene was studied. The effect of liquid carbon dioxide on the polymerization was investigated under conditions of the pressure of 400 kg./cm. 2 over the temperature range 20–45°C. by using γ‐radiation and AIBN as initiators. The infrared spectrum of the polymers showed that carbon dioxide had little effect on the polymer structure. The polymers contained no combined carbon dioxide and only small amounts of vinylidene unsaturation. The methyl content of the polymers was 0.5–4.0 CH 3 /1000C. The polymer yield and molecular weight were found to be decreased by the addition of carbon dioxide in both polymerization by γ‐radiation and AIBN. The number of polymer molecules formed per unit time increased with the content of carbon dioxide in the γ‐ray polymerization, and was constant in the case of AIBN. The advantages of the use of liquid carbon dioxide as a solvent in this polymerization were also considered from the viewpoints of the continuous process, the separation of polymer, the stability of carbon dioxide to radiation, and commercial applications.