Two different polymerization mechanisms of acrylonitrile initiated by γ‐irradiation

Abstract The polymerization of acrylonitrile induced by ionizing radiation was investigated in bulk in the temperature range 15 to −196°C. It was found from this investigation that two different mechanisms could exist in the polymerization under the same conditions in different temperature regions. The two polymerization phenomena at room and at very low temperatures were studied from the point of view of radical and ionic polymerization mechanisms. It has been well known that the polymerization at room temperature proceeds by radical mechanism. In the solid state polymerization at very low temperatures the following results were obtained: first, the activation energy is very low, i.e., ca. 0.4 kcal./mole; second, an induction period was not observed under various conditions; third, the monomer containing a radical scavenger was easily polymerized. The authors believe that the facts described above indicate that polymerization in the solid state should proceed by an ionic mechanism.