Aromatic liquid crystalline copolyesters with low Tm and high Tg: Synthesis, characterization, and properties
Article first published online: 6 FEB 2014
Copyright © 2014 Wiley Periodicals, Inc.
Journal of Applied Polymer Science
Volume 131, Issue 13, July 5, 2014
How to Cite
2014). Aromatic liquid crystalline copolyesters with low Tm and high Tg: Synthesis, characterization, and properties. J. Appl. Polym. Sci. 131, 40487, doi: 10.1002/app.40487, , , , and (
- Issue published online: 3 APR 2014
- Article first published online: 6 FEB 2014
- Manuscript Accepted: 17 JAN 2014
- Manuscript Received: 17 NOV 2013
- thermal properties;
- liquid crystals;
In this study, a series of aromatic copolyesters P-BPAx with lower melting temperature and higher glass transition temperature derived from hydroxybenzoic acid (HBA), 6-hydroxy-2-naphthoic acid (HNA), bisphenol A (BPA) and terephthalic acid (TA) were synthesized via melt polymerization. The copolyesters were characterized by FTIR, solid state 13C NMR, DSC, TGA, polarized optical microscopy, X-ray diffraction, and rheometry measurements. With addition of BPA, the resulting copolyester's melting temperature decreased from 260 to 221°C and its glass transition temperature increased from 70 to 135°C, compared with the parent copolyester P-HBA70 (HBA/HNA copolymer). With exception of copolyester P-BPA5.0 (225–280°C), the copolyesters could maintain liquid crystalline behavior in a broad temperature range from 230°C to higher than 410°C. The ability to form nematic liquid crystalline phase disappeared when BPA concentration became higher than 15 mol %. X-ray diffraction analysis showed crystallinity decreased as the BPA content increased. A slightly distorted O" and a substantially distorted O′ orthorhombic phase was observed for P-BPA2.5. Upon annealing at 220°C, the O" phase disappeared and the O′ phase became stronger gradually. Rheology study data showed the ability to process the copolyesters improved in those compositions containing <2.5 mol % BPA. Continuing to increase concentrations of BPA, they became intractable. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40487.