Bimodal Polyethylene Technology

A bimodal polyethylene having a high density ranging from about 0.955 to about 0.959 g/cc, may be formed using a Ziegler-Natta polymerization catalyst using two reactors in series. The bimodal polyethylene may have a high load melt index (HLMI) of from about 2 and about 30 dg/min and may be optionally made with a small amount of alphaolefinic comonomer in the second reactor. The mechanical properties of bimodal grades, such as stiffness and stress crack resistance, have been significantly improved compared to unimodal resins. Global demand for polyethylenehas grown quickly over many decades. Several companies have developed their own bimodal process technologies. This paper presents importance of this matter and related issues.