Radiation-induced polymerization of ethylene in a pilot plant. I. Bulk process

Radiation-induced bulk polymerization of ethylene was carried out with use of a pilot plant with a 10 liter reactor at pressures of 225 to 400 kg/cm2, temperatures of 30 to 950C, ethylene feed rates of 5 to 28 kg/hr, and dose rate of 3.8 x 105 rad/hr. Characteristics of the process are mild polymerization conditions and capability of producing medium density polyethylene in powder form. The space-time yield and molecular weight of polymer were in the range of 3.5 to 13.1 g/liter hr and 2.2 x 104 to 14 x 104, respectively. The space-time yield increased with mean residence time and 2.4 powders of pressure, and decreased with temperature. Molecular weight changed similarly with the reaction conditions. These results were consistent with those of the bench plant experiment and the scale effect was small. Polymer deposit to the reactor wall limited a period of continuous operation of the plant. The amount of deposited polymer was increased with the square of reaction time. The rate of polymer deposit was proportional to polymer concentration and to the cube of pressure. The polymer deposit cannot be solved in the bulk process. 9 figures, 1 table