Crystal structure and conformational disorder of poly(hexamethylene terephthalate)

✍ Scribed by Katsuhiro Inomata; Shintaro Sasaki

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 753 KB
• Volume: 34
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(19960115)34:1<83::aid-polb6>3.0.co;2-x

✦ Synopsis

Packing polymorphism and conformational disorder of poly(hexamethy1ene 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 B form (135°C) and j 3 ' form (2OOC) were similarly triclinic.

The @' 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 (B form), the chains were indistinguishable by xray diffraction owing to the ring-flipping motion. The p and j3' structures were different in the local conformational disorder around the terephthaloyl groups. Conformational polymorphism of homologous poly(oligomethy1ene terephtha1ate)s was considered to originate from the difference in bulkiness of the aromatic and aliphatic residues. 0 1996 John