Polymer paperThe structure of copoly(4-hydroxybenzoic acid/2-hydroxy-6-naphthoic acid): 2. An atomic model for the copolyester chain☆

Add time:09/09/2019    Source:sciencedirect.com

X-ray fibre diagrams of fibres drawn from the (liquid crystalline) melts of copoly(4-hydroxybenzoic acid/2-hydroxy-6-naphthoic acid) show meridional maxima that are aperiodic. The positions of these maxima are reproduced in calculations of the meridional intensities for completely random copolymer sequences in which the monomers are approximated to points separated by the appropriate monomer lengths. These calculations have now been extended to consider an atomic model for the chains. Comparison of the calculated meridional transforms with diffractometer scans for five monomer ratios shows good agreement, not only for the positions but also for the relative intensities of the observed and calculated maxima. The linewidth of the maximum at d≅2.1 Ǎ depends on the chain length used for the calculations and presents a method for determination of the persistence length of the extended chain conformation.

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