Novel Proposal of Lamellar Clustering Process for Elucidation of Tensile Yield Behavior of Linear Polyethylenes

Abstract

We propose a new solidification process in crystallizable polymers in which lamellar clustering takes place in the crystallization process under high supercoolings. Clustering of lamellae is a two-step process: the first step is the exclusion process of chain ends from the space of a single Gaussian chain accompanied by the cooperative alignment of stiffened segments. This leads to anisotropic cylindrical units including several intertwined chains and is followed by the two-dimensional development of the partially solidified units into the final lamellar cluster. Using a series of polyethylenes with different molecular weights we show that the use of the lamellar cluster model makes it possible to provide a consistent understanding of both the solidification process and tensile yielding behavior in semicrystalline solids. The present model well explains the intercrystalline links found by Keith et al. (J. Polym. Sci. A2 1966, 4, 267–282) and the results which show that the calculation of the strength of the links agree with that of ultra-high-modulus fibers.