Anomalous orientation of poly(trimethylene oxy-2 methyl trimethylene p–p′ bibenzoate) as revealed by means of tensile tests

Bello, Pablo; Bello, A.; Lorenzo, Vicente

doi:10.1016/s0032-3861(00)00718-7

Cited by 20 publications

(30 citation statements)

References 4 publications

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“…1,12,18,19,[57][58][59][60] Figure 24b shows X-ray pattern taken for such a fiber of BB-5. The pattern is similar to that (Figure 24a) of the fiber drawn from the isotropic melt, but quite different in the orientation geometry of reflections with respect to the fiber axis.…”

Section: Unusual Orientation Of Smectic Melt On Uniaxial Stretching Amentioning

confidence: 99%

Several Interesting Fields Exploited through Understanding of Polymeric Effects on Liquid Crystals of Main-Chain Polyesters

Tokita

Watanabe

2006

Polym J

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ABSTRACT:We review our experimental results on the structural characteristics of polymeric liquid crystals collected through our studies on the main-chain liquid crystalline polyesters with mesogenic biphenyl groups connected by flexible alkyl spacer. The polyesters studied, designated as BB-n where n is the number of carbon atoms in the alkyl spacer unit, form smectic mesophases. Of interest is that the type of smectic phase alters depending on the odd-even parity of n. An ordinal smectic A phase is formed by BB-n with even n, whereas BB-n with odd n forms a new type of smectic phase, so called smectic CA phase, in which the long axis of the mesogen is tilted against the layer normal and the tilting direction is opposite between neighboring layers. Finding of smectic CA phase with specific packing symmetry leads to a distinct discovery of ferroelectric and antiferroelectric phases in achiral molecular systems. In these smectic phases, the polymer chain assumes more extended conformation. Such an extended conformation, however, does not continue over the whole length of the polymer and hairpin folding arises to gain entropy. In the smectic phases, the hairpin foldings are located at a limited space, forming chain folded lamellae. Unusual shear flow orientation and anomalous crystallization behavior are explained based on the chain folded lamellar structure. Solid state morphology of liquid crystalline polymer is also presented. Since the degree of liquid crystallinity is almost 100%, the solid phase cooled through the formation of liquid crystals is composed of crystal and liquid crystal glass. Liquid crystal glass is studied and properties are discussed in a comparison with those of conventional isotropic glass.

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Section: Unusual Orientation Of Smectic Melt On Uniaxial Stretching Amentioning

confidence: 99%

Several Interesting Fields Exploited through Understanding of Polymeric Effects on Liquid Crystals of Main-Chain Polyesters

Tokita

Watanabe

2006

Polym J

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“…Polymer PPO4B, like other polybibenzoates [7,8,26], has a peculiar behaviour concerning to the direction in which the smectic planes are oriented. It has been established that the smectic planes can be oriented perpendicular or parallel to the draw direction depending on the rate of deformation and temperature.…”

Section: Molecular Orientationmentioning

confidence: 99%

“…Most of them are concerned with low-ordered mesophases and discuss orientation either by shearing [28][29][30][31][32][33] or by drawing [7,8,26,27,[34][35][36][37]. This interesting phenomenon has been explained [27,35] by assuming that the macromolecules are disposed in domains that can move rather independently, what means that the macromolecular interconnection between domains is scarce.…”

Section: Ppo4bn0mentioning

confidence: 99%

“…It has been proved that the thermal properties of the mesophases and their transformation rates can be controlled with suitable changes in the structure of the flexible spacer [3][4][5][6][7][8][9]. A factor that can be managed is the stiffness of the molecular chains, governed by the number of conformations permitted to the chains, which can be modified by inserting side groups and/or ether groups along the spacer.…”

Section: Introductionmentioning

confidence: 99%

“…These systems allow comparing the properties of the amorphous and liquid-crystalline glasses of thermotropic main chain polymers. Moreover the presence of a single mesophase in a wide interval of temperatures makes easy to study the characteristics and properties of the liquid-crystalline state: the phenomena of anomalous orientation [7,8], for instance.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and structural studies of poly(tetramethyleneoxypropylene p, p´-bibenzoate)

2008

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Abstract:A smectic main chain polybibenzoate has been synthesized using a mixture of the branched ether-diols: HO(CH 2 ) 4 OCH(CH 3 )CH 2 OH and HO(CH 2 ) 4 OCH 2 CH(CH 3 )OH, as flexible spacers. The mesophase has been identified as SmCalt by optical microscopy and X-ray diffraction experiments. The irregular chemical structure of the polymer, due to the asymmetry of the spacers, produce two important effects: the mesophase is stabilized and the liquid crystallization is slowed down, making possible the freezing of the amorphous glass by supercooling the isotropic melt. Therefore, both the amorphous glass and the smectic glass can be obtained and analyzed. By differential scanning calorimetric measurements it was found that the glass transition of the mesophase appears at lower temperature than the glass transition of the amorphous state. Depending on the temperature and rate of deformation, the molecular orientation in the drawn smectic phase can be perpendicular (anomalous orientation) or parallel (normal orientation) to the stretching direction (or a mixture of both orientations). The morphology of these oriented samples has been studied by scanning electron microscopy.

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The role of psychosocial factors in the development of breast carcinoma: Part I

Price

Tennant

Smith

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Cancer

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Anomalous orientation of poly(trimethylene oxy-2 methyl trimethylene p–p′ bibenzoate) as revealed by means of tensile tests

Cited by 20 publications

References 4 publications

Several Interesting Fields Exploited through Understanding of Polymeric Effects on Liquid Crystals of Main-Chain Polyesters

Several Interesting Fields Exploited through Understanding of Polymeric Effects on Liquid Crystals of Main-Chain Polyesters

Synthesis and structural studies of poly(tetramethyleneoxypropylene p, p´-bibenzoate)

The role of psychosocial factors in the development of breast carcinoma: Part I

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