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Wholly aromatic thermotropic liquid crystalline polyesters of 3,3′-bis(phenyl)-4,4′-biphenol with 4,4′-benzophenone dicarboxylic acid

✍ Scribed by Haesook Han; Pradip K. Bhowmik; Kurt C. Frisch

Publisher
John Wiley and Sons
Year
1997
Tongue
English
Weight
373 KB
Volume
35
Category
Article
ISSN
0887-624X

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✦ Synopsis

A series of wholly aromatic, thermotropic polyesters, derived from 3,3-bis (phenyl)-4,4-biphenol (DPBP), nonlinear 4,4-benzophenone dicarboxylic acid (4,4-BDA), and various linear comonomers, were prepared by the melt polycondensation reaction and characterized for their thermotropic properties by a variety of experimental techniques. The homopolymer of DPBP with 4,4 -BDA had a fusion temperature (T f ) at 265ЊC, exhibited a nematic phase, and had a liquid crystalline range of 105ЊC. All of the copolyesters of DPBP with 4,4 -BDA and either 30 mol % 4-hydroxybenzoic acid (HBA), 6-hydroxy-2-naphthoic acid (HNA), or 50 mol % terephthalic acid (TA), 2,6-naphthalenedicarboxylic acid (2,6-NDA) had low T f values in the range of 220-285ЊC, exhibited a nematic phase, and had accessible isotropization transitions ( T i ) in the range of 270-420ЊC, respectively. Their accessible T i values would enable one to observe a biphase structure. Each of the copolymers with HBA or HNA had a much broader range of liquid crystalline phase. In contrast, each of the copolymers with TA or 2,6-NDA had a relatively narrow range of liquid crystalline phase. Each of these polyesters had a glassy, nematic morphology that was confirmed with the DSC, PLM, WAXD, and SEM studies. As expected, they had higher glass transition temperatures (T g ) in the range of 161-217ЊC than those of other liquid crystalline polyesters, and excellent thermal stabilities (T d ) in the range of 494-517ЊC, respectively. Despite their noncrystallinity, they were not soluble in common organic solvents with the exception that the homopolymer and its copolymer with TA had limited solubility in CHCl 3 . However, they were soluble in the usual mixture of p-chlorophenol/1,1,2,2-tetrachloroethane (60/40 by weight) with the exception of the copolymer with 2,6-NDA. ᭧ 1997

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