Epitaxial crystallization of polyethylene on organic substrates: A reappraisal of the mode of action of selected nucleating agents

Abstract

Electron microscopy and electron diffraction studies show that polyethylene crystallizes epitaxially onto crystals of homologous series of (i) condensed aromatic hydrocarbons and (ii) linear polyphenyls. The contact planes of the PE chain‐folded lamellae with the (001) faces of the substrate crystals are found to differ for the two series, being (100) and (110), respectively. The underlying epitaxial relationships are best explained by a two‐dimensional lattice matching of polymer and substrate networks. In view of the structural similarities of the present substrates and some well‐known nucleating agents for polyethylene, epitaxy is suggested as a possible mechanism which could explain the nucleating ability of the latter. This is experimentally demonstrated with the potassium salt of phthalic acid.