低容度 폴리에틸렌을 生産하는데 있어서 品質管理를 爲하여 long-chain branching을 control하는 일이 대단히 중요하다. 그 理由는 long-chain branching이 生産된 低密度 폴리에틸렌의 流動學的 物性과 加工性에 큰 영향을 주기 때문이다. 高壓下에서 生産되는 폴리에틸렌 反應器의 특징은 管狀反應器를 使用하는 경우에 그 길이가 直徑의 230倍 내지 1,200倍나 된다는 點이다 生産費의 상당한 額數가 에틸렌을 壓縮시키는데 所要되므로 傳化率을 增加시킬 수 있다면 生産費를 크게 감축시킬수 있다. 이의 한 方法으로서 initiator나 單量體 또는 兩者를 同時에 反應器의 여러 位置에서 加하여 주는 것(multiple injections)이 좋다고 文獻에 報告되어 있다. 著者들은 이러한 提示를 證明하기 爲하여 理論的인 硏究를 遂行하였으며 反應器內에서의 溫度分布, 單量體 및 initiator의 傳化率, 分子量 分布度等의 代表的인 結果를 報告하는 바이다.

In the production of polyethylene under high pressure, yielding so called "low-density polyethylene," control of the long-chain branching reaction is of paramount importance to product quality. This is because the long-chain branching level influences the rheoloaical properties and processability of the polyethylene produced. The high pressure polyethylene tubular reactor is characterized by its large length-to-diameter ratio which ranges from 250:1 to as high as 1200:1. Since a significant portion of the production cost of polyethylene in a high-pressure tubular reactor is attributed to the power consumption needed to compress the ethylene, an increase in conversion should help reduce the production cost considerably. It has been suggested in the literature that the use of multiple injections of initiator and/or monomer can increase the conversion of ethylene considerably. We have recently investigated the performance (the conversion and product quality) of a high-pressure polyethylene tubular reactor with multiple injections of initiator and monomer. As part of the investigation, temperature profiles, monomer and initiator conversion, and the number-and weight-average molecular weights were calculated along the length of the reactor. In this paper, we shall present some of the highlights of the study.