Abstract：The development status of bimodal polyethylene was introduced and the self-produced 1-butene copolymer product was compared with the imported 1-hexene copolymer product. The microstructure difference was analyzed by gel permeation chromatography (GPC), differential scanning caborimetry (DSC), Fourier infrared spectroscopy (FTIR), and so on. It was found that the length of short branched-chain had a more significant effect on the anti-chronic crack growth of bimodal polyethylene than the number of short branched-chain. The bimodal polyethylene with longer branched-chain and shorter interbranched-chain segments had better anti-chronic crack growth performance. Based on this, the quality indexes of high-performance bimodal high density polyethylene (HDPE) gas pipe material were proposed: the weight-average molecular weight was 200 000-240 000, the comonomer was C6 or α-olefin with longer length, the content of comonomer was 0.8%-2.5%, the crystallinity was 50%-57%, and the molecular weight distribution was 15-35. The industrial trial production results showed that the product had excellent resistance to slow crack growth.
