Theory of polymer crystallization without chain folding

A theoretical treatment of nucleation-controlled polymer crystal growth is developed. A distinction is made between the end-surface energy of the crystal lamella and that of the nucleus for growth. The growth rate is related to the nucleation frequency using a thick-crystal treatment, and the lamellar thickness is viewed as limited by diffusion of the crystallizing chain in the liquid. Exponential growth kinetics are predicted by the model, and when compared with available experimental data on polyethylene, a reasonable value for the end-surface energy of the nucleus is obtained. The lamellae formed at a given under-cooling are expected to be distributed over a range of thicknesses, with a most probable value of about twice the minimum thickness stable at the undercooling.