ISSN:
0887-6266
Keywords:
poly(hexamethylene terephthalate)
;
x-ray diffraction
;
polymorphism
;
conformation
;
crystal structure
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Packing polymorphism and conformational disorder of poly(hexamethylene terephthalate) were analyzed by x-ray diffraction technique. The measurements were performed in the temperature range from 20 to 135°C. At high temperature, several unassignable reflections were found to disappear, and all reflections were satisfactorily indexed by single-chain unit cell. The crystal structures of β form (135°C) and β form (20°C) were similarly triclinic. The β′ unit cell assumed the double b-axis dimension, and the centrosymmetric conformations of the two chains adjacent along the b-axis differed in the orientation of the phenylene rings. At the elevated temperature (β form), the chains were indistinguishable by x-ray diffraction owing to the ring-flipping motion. The β and β′ structures were different in the local conformational disorder around the terephthaloyl groups. Conformational polymorphism of homologous poly(oligomethylene terephthalate)s was considered to originate from the difference in bulkiness of the aromatic and aliphatic residues. © 1996 John Wiley & Sons, Inc.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
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