| Popis: |
In a paper 6 years ago, we reported on the detailed molecular structure of lamellar crystalline high pressure polymerized polyethylenes rich in branching. We showed that the crystalline cores contained few ethyl and butyl side-branches but did contain long side chains. In this paper, we exploit recent developments in technique to refine our observations, improve their rigour and extend them to commercially significant high-pressure polymerized polyethylenes of modest side-branch content. We also study and report on some common ethylene olefin copolymers. We conclude that our earlier conclusions are correct, that the side-branches are bunched rather than being randomly situated along the backbones and that most of the branches, and in particular the branched branches, become concentrated in the inter-core regions on melt crystallization. |
