Synthesis conditions and structure of low density polyethylene. I. Short and long chain branching

Abstract In order to further our knowledge about the effect of synthesis conditions on the structure and properties of low density polyethylene, a large number of polymer samples was prepared at temperatures between 100 and 300°C and at pressures from 1100 to 2000 bar. A continuously operating polymerization plant with 3 agitated autoclaves each of different geometry was available for the synthesis. The aim was to use various organic peroxides and oxygen in order to find out whether the properties of the polyethylene produced also depend on the initiator. An analysis of the polymers revealed that high temperatures promote the formation of both short and long side chains which are characteristic of low density polyethylene. High pressures reduce the amount of branching. The type of initiator was not found to have any effect but a change in reactor geometry affects the long chain branching because of the accompanying change in temperature distribution.