On interfering nuclei and their novel kinetics during the crystallization of polyethylene from the melt

At high temperatures, linear polyethylene crystallizes from the quiescent melt as lamellae with inclined, similar to {201}, fold surfaces. Accordingly, when grown on linear nuclei to form row structures, the first lamellae to form do so epitaxially in two orientations symmetrically inclined to the axis of the row. With increasing radial distance, dominant lamellae widen, separate and become normal to the row albeit still with inclined fold surfaces. Isothermal growth rates are constant in both conditions but that for the later one is 3-4 times faster than the initial one. It is suggested that faster growth is a consequence of diminishing interference between secondary nuclei on neighbouring lamellae growing under Regime I conditions. The concept of interfering nuclei, competing for the same molecule, also provides a convincing explanation for previously reported kinetic effects in polyethylene and long n-alkanes as well as the presence of faster-growing dominant lamellae in the crystallization of such linear molecules. (C) 2001 Elsevier Science Ltd. All rights reserved.