The mechanism of the high‐pressure free radical polymerization of ethylene

The reaction path of the free radical polymerization of ethylene is usually considered identical to the polymerization mechanism of other vinyl monomers. Available experimental data on the polymerization of ethylene, however, hardly fitted the well-established path of free radical polymerization. Obviously the mechanism of ethylene polymerization is more complex and not well understood. One reason for this, in our opinion, is insufficient knowledge of the physicochemical state of ethylene under high pressure. A model that described the behavior of ethylene under compression has been proposed. According to the model, and increase in pressure causes the formation of various supermolecular forms of ethylene, each accompanied by transition of the second order. By proposing a stereochemical shape for each supermolecular form calculation of activation volumes for each of these transitions was made. Good agreement was obtained when calculated volumes of activation were compared with corresponding experimental values in the literature.