Effect of isotropization on the thermal behavior of two thermotropic copolyesters containing spirobicromane moieties

Lin, Lieh-Li; Hong, Jin‐Long

doi:10.1016/s0032-3861(00)00471-7

Cited by 9 publications

(9 citation statements)

References 10 publications

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“…All obtained polymers showed fine textures, difficult to ascribe, similar as reported for thermotropic polyesters based on terephthaloyl-bis(4-oxyphenylene carbonyl) units [12,[28][29][30]. The transition temperature from crystal to liquid-crystalline melt was in the range of 216-2598C and depends on the nature of aromatic bisphenols 2.…”

Section: Liquid Crystalline Propertiesmentioning

confidence: 51%

“…The objectives of designing melt processable polyesters with nematic structure are to reduce the melting temperature bellow the thermal stability limit and to obtain a melt that remains nematic until the onset of decomposition. The structural modifications that are commonly used to control the T m values of this class of polymers include the following: copolymerization of different sizes of mesogenic (LC forming) monomers to lower the symmetry of the polyester primary structure; the introduction of substituents of various sizes on either the aromatic dicarboxylic acid, the aromatic diol or both moieties to disrupt lateral packing; the introduction of noncoplanar 2,2 0 -substituted-4,4 0 -biphenols and 2,2 0 -substituted-4,4 0 -biphenylenedicarboxylic acids, and other structurally similar monomers to cause a reduction of inter-chain interactions; the introduction of kinked or bent (nonlinear) monomers to lower the persistence length of the polyester in the LC phase and to disrupt lateral interactions in the solid state [6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and properties of new aromatic copolyesters containing phosphorous cyclic bulky groups

Vlad‐Bubulac¹,

Hamciuc²

2010

Polymer Engineering & Sci

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A series of phosphorus-containing copolyesters was prepared by polycondensation of 2-(6-oxido-6H-dibenz<1,2>oxaphosphorin-6-yl)-1,4-naphthalene diol, 1, or of an equimolecular amount of 1 and different bisphenols 2, such as 4,4 0 -isopropylidenediphenol, 4,4 0 -(hexafluoroisopropylidene)diphenol and 2,7-dihydroxynaphthalene, with an aromatic diacid chloride containing two preformed ester groups 3, namely, terephthaloyl-bis-(4-oxybenzoyl-chloride). The copolyesters exhibited good thermal stability having the temperature of 5% weight loss above 3808C and char yield at 7008C in the range of 20-31.2%. The glass transition temperature was in the range of 136-1478C. The polymers exhibited thermotropic liquid crystalline behavior, as was observed with polarized optical microscopy, differential scanning calorimetry, and X-ray experiments.

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Section: Liquid Crystalline Propertiesmentioning

confidence: 51%

Section: Introductionmentioning

confidence: 99%

Synthesis and properties of new aromatic copolyesters containing phosphorous cyclic bulky groups

Vlad‐Bubulac¹,

Hamciuc²

2010

Polymer Engineering & Sci

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“…This phenomenon of multiple melting was reported in many papers as a feature in common for liquid crystalline polyesters. [8,10,[37][38][39] The multiple melting behavior has been previously attributed to reasons including the presence of different crystal structures, [40,41] or to crystal reorganization, [42,43] or to different components of the morphology formed in multiple stages of crystallization. [44] DSC traces of polymers 4a-4d have similar features.…”

Section: Thermal Analyses: Thermal Transitionsmentioning

confidence: 99%

“…[8][9][10]45,46] Upon cooling from the isotropic state the polymers 4 behave differently as a function of the aliphatic content. The flexible methylene spacer groups separate the mesogenic alignment, thereby reducing the overall rigidity.…”

Section: Thermal Analyses: Texture Analysismentioning

confidence: 99%

“…There are some papers which have been published that show the ability of polyesters derived from stiff mesogenic units containing two or three aromatic moieties connected by suitable ester or ether linkages to form thermotropic liquid crystals. [8][9][10][11] On the other hand, in many applications, for example, structural materials for aircraft, electric and electronic applications, wiring applications or automotive production, the common polymers (polyethylene 1,4-terephthalate (PET), or polyethylene 2,6-naphthalate (PBT)) cannot satisfy the high thermal and fire retardant requirements. [12] Several approaches have been attempted to modify these drawbacks.…”

Section: Introductionmentioning

confidence: 99%

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Structure and Properties of Phosphorous‐Containing Thermotropic Liquid‐Crystalline Aliphatic–Aromatic Copolyesters

Serbezeanu¹,

Vlad‐Bubulac²,

Hamciuc³

et al. 2010

Macro Chemistry & Physics

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A series of thermotropic liquid crystalline aliphatic–aromatic copolyesters derived from various ratios of dodecane‐1,12‐diol (1), terephthaloyl bis‐(4‐oxybenzoyl‐chloride) (2), and 2‐(6‐oxido‐6H‐dibenz〈c,e〉〈1,2〉 oxaphosphorin‐6‐yl)‐1,4‐naphthalene diol (3), has been synthesized. The chemical structures of the monomers and polymers have been confirmed by elemental analyses, and FT‐IR and 1H NMR spectroscopy. The mesomorphic properties of polymers have been investigated by differential scanning calorimetry, polarizing optical microscopy, and X‐ray diffraction measurements. The influence of the content of the aliphatic unit on the phase behavior of the polymers has been examined. The polymers that contain >30 mol‐% aliphatic diol showed smectic phases while the polymers that contained <30 mol‐% aliphatic diol displayed nematic phases. The polymers revealed a reversible mesomorphic phase transition, wide mesophase temperature ranges, and high thermal stability. The degree of crystallinity increased upon increasing the content of aliphatic moieties. The char yield at high temperature increased by increasing the content of phosphorous‐containing bisphenol.magnified image

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Synthesis and properties of novel phosphorus‐containing thermotropic liquid crystalline copoly(ester imide)s

Serbezeanu¹,

Vlad‐Bubulac²,

Hamciuc³

et al. 2010

J. Polym. Sci. A Polym. Chem.

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A series of novel phosphorus‐containing polyesterimides were prepared from diols—a mixture of a new aromatic phosphorus‐containing bisphenol, namely 1,4‐bis[N‐(4‐hydroxyphenyl)phthalimidyl‐5‐carboxylate]‐2‐(6‐oxido‐6H‐dibenz<1,2>oxaphosphorin‐6‐yl)‐naphtalene, with aliphatic diols such as 1,3‐propanediol, 1,4‐butanediol, 1,5‐pentanediol, 1,6‐hexanediol, and 1,12‐dodecanediol—and an aromatic diacid chloride containing two preformed ester groups, namely terephthaloyl‐bis‐(4‐oxibenzoyl‐chloride), via high‐temperature polycondensation in o‐dichlorobenzene. The structures of monomers and polymers were verified by means of Fourier transform infrared (FTIR) spectroscopy and 1H NMR spectroscopy. The molar ratio of aromatic bisphenol to aliphatic diol was varied to generate a series of copolyesterimides with tailored physicochemical properties, structure–properties relationships being established. The effect of the phosphorus content on the thermal properties and the flame retardancy was evaluated by means of thermogravimetric analysis (TGA), TGA–FTIR, and scanning electron microscopy. The polymers were stable up to 340 °C showing a 5% weight loss in the range of 340–395 °C and a 10% weight loss in the range of 370–415 °C. The char yields at 700 °C were in the range of 13.6–38% increasing with the content of phosphorus‐containing bisphenol. The effect of the aliphatic content on the liquid crystalline behavior was investigated by polarized light microscopy, differential scanning calorimetry, and X‐ray diffraction. The transition temperatures from crystal to liquid crystalline melt were in the range of 209–308 °C. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

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Effect of isotropization on the thermal behavior of two thermotropic copolyesters containing spirobicromane moieties

Cited by 9 publications

References 10 publications

Synthesis and properties of new aromatic copolyesters containing phosphorous cyclic bulky groups

Synthesis and properties of new aromatic copolyesters containing phosphorous cyclic bulky groups

Structure and Properties of Phosphorous‐Containing Thermotropic Liquid‐Crystalline Aliphatic–Aromatic Copolyesters

Synthesis and properties of novel phosphorus‐containing thermotropic liquid crystalline copoly(ester imide)s

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