Influence of aryl substituents on the thermal and solubility behavior of poly(<i>p</i>‐phenylene terephthalate) and poly(<i>p</i>‐phenylene terephthalamide)

Hatke, Wilfried; Land, Horst‐Tore; Schmidt, Hans‐Werner; Heitz, Walter

doi:10.1002/marc.1991.030120406

Cited by 27 publications

(23 citation statements)

References 10 publications

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“…In this article we describe the preparation and properties of a series of thermotropic polyesters containing both homopolyesters of 3,4'-DHB and its copolyesters with 50 mole % of each of the aromatic dicarboxylic acid pair as part of an extensive study on the structure-property relationship of this class of polymers in our laboratory. The aromatic dicarboxylic acids used were TA, 2,6-NDA, and 4,4'bibenzoic acid (4,4'-BBA) . However, it is important to note that 4,4'-BBA is a potential, mesogenic diacid, which has been extensively studied in the field of semiflexible thermotropic polyester^.^^-'^ To date, there are a few reports of fully aromatic, thermotropic polyesters containing this dia~id.~' The two principal reasons are possibly the following: first, 4,4 '-bibenzoic acid is a potential smectogenic monomer in contrast to 4,4'-biphenol, which is a nematogenic monomer;30 second, this diacid has the greatest length when compared to those of T A and 2,6-NDA, which may increase the T, too high to form an LC phase, therefore, it was of interest to prepare and characterize both a homopolymer and a few copolymers containing this diacid with 3,4'-DHB.…”

Section: -2mentioning

confidence: 99%

Fully aromatic thermotropic liquid crystalline polyesters of 3,4′‐dihydroxybenzophenone

Han

Bhowmik

Lenz

1994

J. Polym. Sci. A Polym. Chem.

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SYNOPSISA series of fully aromatic, thermotropic polyesters, derived from 3,4'-dihydroxybenzophenone and various aromatic dicarboxylic acids, was prepared by the high-temperature solution polycondensation method and examined for thermotropic behavior by a variety of experimental techniques. The aromatic dicarboxylic acids used in this study were 2,6-naphthalenedicarboxylic acid, 4,4'-hibenzoic acid, and terephthalic acid.The two homopolymers of 3,4'-DHB with either 2,6-NDA or 4,4'-BBA formed nematic LC phases a t 285°C and 255°C and also exhibited isotropization transitions (Ti ) at 317°Cand 339"C, respectively. The copolymer of 3,4'-DHB with 50% TA and 50% 2,6-NDA also formed a nematic LC phase and had a broader range of LC phase than that of its respective homopolymers. Two other copolymers of 3,4'-DHB, both containing 50% 4,4'-BBA, also formed nematic LC phases a t low T, values. All of the thermotropic polyesters had high thermal stabilities.

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Section: -2mentioning

confidence: 99%

Fully aromatic thermotropic liquid crystalline polyesters of 3,4′‐dihydroxybenzophenone

Han

Bhowmik

Lenz

1994

J. Polym. Sci. A Polym. Chem.

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“…The thermal stability limit, T d , which was taken as the temperature (°C) at which a 5% weight loss of a sample occurred, varied from 413 to 436 °C in nitrogen indicating that each of them had an excellent thermal stability for the melt processing in its nematic LC phase, as discussed below, at the elevated temperature. Their thermal stability was essentially similar to that of either the copolymer of ClHQ or the copolymer of PhHQ, each of which contained equimolar amounts of TA and OBBA. , Additionally, their thermal stability was lower than that (490−500 °C) of the Vectra family of copolyesters (HBA/HNA) under identical experimental conditions . This lower thermal stability when compared with HBA/HNA copolyesters was presumably related to the presence of flexible OBBA unit present in each of the copolyesters.…”

Section: Resultsmentioning

confidence: 91%

Crystalline and Liquid Crystalline Polyesters of Phenyl-Substituted 4,4‘-Biphenols. 5. Copolymers with 4,4‘-Oxybis(benzoic acid)

et al. 1996

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Wholly aromatic, thermotropic copolyesters, derived from either 3-phenyl-4,4‘-biphenol (MPBP) or 3,3‘-diphenyl-4,4‘-biphenol (DPBP) with either terephthalic acid (TA) or 2,6-naphthalenedicarboxylic acid (NDA) and 50 mol % 4,4‘-oxybis(benzoic acid) (OBBA), were prepared by the melt polycondensation reaction, and their liquid crystalline properties were characterized by a number of experimental techniques. The solubility of these polyesters in common organic solvents had also been studied. They had lower fusion temperatures, T f, than the T m values of the copolyesters of 4,4‘-biphenol, TA, and 4-hydroxybenzoic acid. Their low T f values were because of increased entropy of the respective monomers. Each of them exhibited a nematic phase above its T f value that contained both the threaded and schlieren texture. The two copolyesters of MPBP and hand-drawn fibers therefrom showed a banded texture that could be preserved for a prolong period of time. Each of them showed a nematic-to-isotropic transition as determined by the polarizing light microscope studies. The copolyesters of MPBP had a much broader range of mesophase than those of DPBP. The two copolyesters of DPBP exhibited a biphase behavior at lower temperatures than those of the copolyesters of MPBP. Their random microstructures were confirmed with the WAXD studies of oriented fibers and the 13C-NMR spectroscopy, whenever possible. No development of crystallinity occurred in these copolyesters even on annealing. They had relatively high glass transition temperatures, T g, in the range of 149−171 °C when compared with other liquid crystalline polyesters and good thermal stability, T d, in the range of 413−436 °C. Since they had no detectable crystallinity, the copolyesters of either MPBP or DPBP with TA and OBBA were soluble in common organic solvents, but those with NDA and OBBA were not soluble in these solvents.

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“…A vigorous reaction occurred yielding a light pink solution. After 10 min of stirring, 8.5 g (0.084 mol) of triethylamine was added followed by 20 mL of dichloromethane. The reaction was stirred for 1 day, and the resulting triethylamine hydrochloride precipitate was filtered and discarded.…”

Section: Nn'-bis (Benzoy1)-nn'-dimethyl-14butanediamine Model Commentioning

confidence: 99%

Polyamides based on diamines and N, N′‐dimethyldiamines derived from biphenol

McCarthy

Lenz

Kantor

1994

J. Polym. Sci. A Polym. Chem.

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SYNOPSISAromatic-aliphatic polyamides containing a biphenyl mesogen were prepared by both interfacial and solution polymerization reactions. Substitution of the amide nitrogen with methyl groups yielded polymers with significantly different properties than the unsubstituted polyamides. The methyl-substituted polyamides had improved thermal stability, significantly lower melting temperatures, and greater solubility in common solvents. Copolyamides were also synthesized which contained different flexible spacer units that varied in the number of methylene groups. No evidence for the presence of liquid crystalline phases could be obtained in either the unsubstituted polyamides or polyamides containing N-methylated amide units.

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Influence of aryl substituents on the thermal and solubility behavior of poly(p‐phenylene terephthalate) and poly(p‐phenylene terephthalamide)

Cited by 27 publications

References 10 publications

Fully aromatic thermotropic liquid crystalline polyesters of 3,4′‐dihydroxybenzophenone

Fully aromatic thermotropic liquid crystalline polyesters of 3,4′‐dihydroxybenzophenone

Crystalline and Liquid Crystalline Polyesters of Phenyl-Substituted 4,4‘-Biphenols. 5. Copolymers with 4,4‘-Oxybis(benzoic acid)

Polyamides based on diamines and N, N′‐dimethyldiamines derived from biphenol

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