In order to study the mechanical properties of high polymer on the basis of their molecular structure, it is necessary to know the elemental structure of polymeric substances. Recently it was found that the single crystal is a fundamental structure in addition to the original fringe micell model. Here the growing process and the structure of the single crystals are discussed briefly, on the basis of which the elastic properties, the viscoelastic absorption and the drawing processes are

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... . Screw dislocations with a spiral structure often grow on a single crystal. The Burgers vector of the screw dislocation in the crystal of metal is of the order of atomic distance, while that of polymer single crystal is equal to the thickness of the crystal itself, that is about 100A. This may be due to the much lower elastic modulus of single crystal of high polymer. In metal and other inorganic salts, the plastic properties as well as the growth mechanism are explained in term of the screw dislocation. On the other hand, in the case of polymer, the roles played by dislocation on their mechanical properties are not yet clear. The fold conformation of the polymer chain induces a stress in the surface layer of the lamellae and this stress can be released by twisting the lamellae. The critical stress inducing the twisting and the period of the twist are represented in terms of the thickness, the width, the rigidity, the Young's modulus of the lamellae, the strain in the surface and the thickness of the strain layer.