Crystal structures, polymers sample history dependence

In this article we have reviewed our recent work with NMR analysis on various kinds of linear polyethylene samples. It has become evident that the refined NMR analysis gives us much important information on the phase structure of samples in terms of molecular mobility, and establishes that there is no unified phase structure for polymer samples. The phase structure of samples varies over a very wide range, depending strongly on the sort of samples involved as well as on the mode of crystallization or the history of those samples. We should emphasize that there are significant differences in phase structure among the bulk-crystals, the solution-crystals, and the fiber samples, particularly in the conformation of molecular chains in the noncrystalline content. We should not confuse these phase structures with each other. The phase structures are evidently different, sample by sample, as their macroscopic properties also differ one from another. 

Polymer liquid crystals generally form unusual textures, accompanied by complex and unstable superstructures. Such textures depend on a sample history, especially mechanical and thermal histories, and also on the surface nature of the vessels. We have described the structural characteristics of polymer liquid crystals under a shear force by means of rheo-optical methods. ... 

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