Short chain branching in high density polyethylene: 13C n.m.r. study

The character and amount of branching has been determined by ¹³C. n.m.r. spectroscopy, in a series of samples of high density polyethylene (HDPE) and in some ethylene copolymers of high density. HDPE samples prepared by different methods were studied and only methyl branches were found; however, the number of branches differs considerably in various polymers. The quantitative determination of the branches is in good agreement with the results of infra-red spectroscopy. The relation between the type of branches and the crystallinity of polyethylene is discussed.