AbstractThe radiation‐induced polymerization of ethylene was carried out by use of a benchscale plant with a flow‐type reactor of 1 liter capacity under the following conditions: pressure, 200–400 kg/cm2; temperature, 30–90°C; irradiation intensity, 3.8 × 105rad/hr; and ethylene flow rate, 300–3000 nl/hr. The molecular weight of polymer formed was shown to decrease with increasing reaction temperature and to increase with increasing pressure. When the ethylene flow rate increases, the molecular weight decreases in the polymerization at 30–60°C, but it does not change in the polymerization at 75–90°C. Methyl group content, which is a measure of short‐chain branching of the polymer, increases with increasing reaction temperature, i.e., ca. 1 CH3/1000 CH2at 30°C and ca. 9 CH3/1000 CH2at 90°C. Methyl content is independent of the ethylene flow rate. The changes in the melt index of polymer with reaction conditions corresponds to the change of the molecular weight. The density, crystallinity, and melting point of polymer decrease with the reaction temperature as the short‐chain branching increases, and they are almost independent of ethylene
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