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首页> 美国政府科技报告 >X-Ray Diffraction by Thermotropic Main-Chain Polymers Having Side Groups. Part C. Semiflexible Polyesters
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X-Ray Diffraction by Thermotropic Main-Chain Polymers Having Side Groups. Part C. Semiflexible Polyesters

机译：具有侧基的热致主链聚合物的X射线衍射。部分C.半柔性聚酯

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It is possible to regain some of the tensile properties that are sacrificed when flexible spacers are inserted periodically in a rigid polymer chain by aligning the chains parallel to each other. One way to do this is to utilize the dipoles present on the anisometric monomers along the chain by placing the liquid-crystalline polymer(LCP)in a magnetic field. Because of their relatively high viscosity, alignment of LCP chains requires fairly strong magnetic fields. An alternative means of aligning the chains is provided by mechanical shear, either by drawing fibers or producing sheets, thus regaining some of the anisotropic mechanical properties of the LCPs themselves. The present study was undertaken to determine the molecular 'structure' of semiflexible polyesters having comparable molecular structures to the more rigid LCPs discussed in Part B of this series by employing the relative intensities of all recordable x-ray reflections, as well as their disposition in reciprocal space. Semiflexible thermotropic aromatic polyesters with lateral groups were aligned magnetically and mechanically in monodomains after separation into high-molecular-weight(polymer)and low-molecular-weight(oligomer)fractions. Based on the total x-ray intensity distributions recorded for a series of seven different substituents in the arylsulfonyl substituted group, a novel smectic structure was determined for Hydrogen, Fluorine, Chlorine, Methoxyradical, and Methylradical in the para-position while a normal nematic alignment prevailed when it contained Bromine or Nitrogen dioxide. (aw)

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