A study on the relation between chain folding and chain length in polyethylene

Abstract

After some preliminary experiments on thermal degradation products, fractions of polyethylene were obtained by solvent extraction. The large periodicities and melting points of these fractions, as crystallized from solution, were measured and the molecular weights of some of the fractions were determined. It was concluded that the molecules must be folded in all except the lowest fraction. The fold length was found to be independent of the length of the molecules. For the lowest fraction all measurements point to the fact that the chains are essentially straight as in the case of paraffins. This result appears to establish the continuity between the crystallization of paraffins and polyethylenes. It is pointed out, however, that this good agreement of different data is surprising in view of the necessary inhomogeneity of the fraction itself.