Studies on Crystallization, Structure and Morphology of Urea-Polyethylene Complex

Abstract

Two preparation methods, "substitutional method" and "direct method" for obtaining ureapolyethylene complex are presented, and then the crystallization mechanism in these methods has been clarified. In the former method, a large crystal of urea-polyethylene complex was prepared by using a starting single crystal of urea-tetracosane complex. X-ray diffraction patterns of these complexes were interpreted in terms of the disordered lattices of the guest molecules. Effects of molecular weight of the guest components on the morphologies of ureapolyethylene complexes prepared by the latter method were studied by the scanning electron microscopy. It was indicated that the formation of shish-kebab crystals of polyethylene on the surfaces of the complex and morphology of polyethylene crystals obtained by the decomposition of the complex with methanol are attributed to the extended chain conformation of polyethylene molecules in the urea tunnels.