Solid-state CP/MAS carbon-13 NMR study of thermotropic aromatic polyester containing a flexible spacer in the main chain

Uryu, Toshiyuki; Kato, Takashi

doi:10.1021/ma00180a015

Cited by 31 publications

(25 citation statements)

References 14 publications

(19 reference statements)

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“…25, No. 1,1993 transition of crystalline-isotropic melt. In order to know how the hydrogen bonding interaction affects the formation of mesophases in polyurethanes 3, thermal processing IR measurements were carried out.…”

Section: Resultsmentioning

confidence: 99%

“…The degree of crystallinity was measured on powder samples by a diffraction of Macscience Co. type MXP 18V using radiation. The scattering intensity was registered at 2° min- 1 for values of 2 e ranging from 4° to 40°. The small-angle X-ray diffraction pattern of 3e was taken in the solid phase, that prepared from quenching rapidly to liquid nitrogen just after annealed at 170°C for 30 min.…”

Section: Diolmentioning

confidence: 99%

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Preparation and Properties of Polyurethanes Containing Mesogenic Units

Sugiyama

Shiraishi

Kato

1993

Polym J

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Section: Resultsmentioning

confidence: 99%

Section: Diolmentioning

confidence: 99%

Preparation and Properties of Polyurethanes Containing Mesogenic Units

Sugiyama

Shiraishi

Kato

1993

Polym J

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“…The peak assignment was carried out according to the literature. 19,20 Comparing the spectrum (C) for the crosslinked, EB-polymerized polymer with the spectrum (B) for the soluble polymer, there was little difference between both solid-state spectra, though the former spectrum exhibited high noise level. Thus, it was suggested that the crosslinking might be caused by a small degree of scission of the epoxy group which was not detectable by NMR spectroscopy or by a reaction caused by an activated epoxy group.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Solid-State Polymerization of Liquid-Crystalline Acrylic Monomers Containing Chiral Epoxy Groups

Shindo

Uryu

1990

Polym J

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ABSTRACT:Solid-state polymerization of liquid-crystalline monomers by low energy electron beam was examined. Six kinds of mono-functional acryloyl monomers having phenyl benzoate as mesogen were synthesized. Of them, two monomers had a chiral epoxy group as well. All polymers and monomers were studied by differential scanning calorimetry, cross-polarizing microscopy and NMR. The presence of the epoxy group stabilized liquid-crystalline phase. In spite of mono-functional acryloyl monomers, monomers containing an epoxy group gave insoluble crosslinked polymers by EB irradiation, while radical polymerization provided a soluble polymer. The solid-state CP IMAS 13C NMR spectrum of the crosslinked polymer was similar to that of a radically-polymerized, linear polymer. DSC and crosspolarizing microscopy measurements exhibited that the crosslinked polymer had phase transition due to crystal-to-smectic, smectic-to-nematic and nematic-to-isotropic changes. The X-ray diffraction pattern showed an orientation of mesogen in EB-polymerized polymers.KEY WORDS Electron Beam I Solid-State Polymerizarion I LiquidCrystalline Polymer I Epoxy Group I In industrial production by curing and polymerization of resins, radiation processing has several advantage over thermal processing. Recent developments related to the radiation processing cover wide fields such as coatings, magnetic media, and adhesives. 1 Radiationcurable resins often consist of acrylic-oligomers and their mixtures with reactive monomers. For radiation-polymerized oligomers, there are reports on the morphology and mechanical properties 2 and the behavior of electron-beam (EB) curing. 3 We have also studied the EB polymerization of acrylic monomer-polymer systems, revealing that the obtained polymer films have good properties as pressure-sensitive adhesives. 4 ,5 polymers, side-chain type liquid-crystalline polymers possess several advantages for the material of recording over main-chain type liquid-crystalline polymers. 6,7 In addition, polymers with ferro-electric propertyB and optical recording property9 have been investigated, Previously, we reported the solid-state polymerization of acrylic 0ligomers 1o and of liquid-crystalline monomers having mesogenic biphenyl groups and terminal acryloyl groups 11 by low energy electron beam, Thermotropic liquid-crystalline acryloyl monomers were highly ordered monomers and seem to have intermolecular interactions. Therefore, these compounds are expected to be converted from monomers to polymers in high yield in the solid-state polymerization, In addition, optically active compounds may have Thermotropic liquid-crystalline polymers have been applied for producing materials for ultrahigh modulus and recording. Of these 336 Polym.

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“…The decrease of the tensile strength may result from the relaxation of molecular orientation which is caused by easy molecular motion by long time annealing at 220°C. Uryu et al 18 reported that the chain conformation transforms from trans to gauche by long time annealing for the TLC polymer with the flexible spacers. The change of conformation occurs the relaxation of molecular orientation.…”

Section: Heat Treatment Of the Polyesteramide Fibersmentioning

confidence: 99%

Effect of the Rigid Units Content on Tensile Properties of the Thermotropic Liquid Crystalline Polyesteramides

Kim

1998

Polym J

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ABSTRACT:The effects of the rigid units content on tensile properties of thcrmotropic liquid crystalline (TLC) polyesteramides with bulky side group were investigated by wide-angle X-ray diffraction (W AXD), scanning electron microscopy (SEM), and tensile measurements. The LC phase and relaxation times of TLC polyesteramides were largely dependent on the amount of rigid units. The as-spun fiber of the copolyesteramide (X = 0.7) having large amount of rigid units exhibited higher tensile properties than that of the homopolyesteramide (X = 1.0). The high tensile strength of copolyesteramide could be explained by the longer relaxation time and better LC property due to the increase of the amount of rigid unit in the molecular chain. The tensile strengths decreased by annealing at 220°C spun fiber, the decrease of tensile strength became dominant in high draw ratio region. It may be attributed to the relaxation of molecular orientation by long time annealing at 220°C. KEY WORDSThermal History/ Rigid Unit/ Thermotropic Liquid Crystalline Polyesteramides / Tensile Properties / Over the past twenty years a number of technologies have emerged for producing highly oriented polymeric materials. 1 ' 2 These successful approches fall into two distinct classes: I) the careful manipulation of conventional polymers into extended chain structures of near perfect molecular orientation in the solid state and 2) the design of rod-like molecules which exhibit nematic liquid crystalline behavior in the melt or solution and transform easily into the orientation structure. Thermotropic liquid crystalline (TLC) polymers which exhibit nematic LC phase in molten state produce a high degree of molecular orientation during melt processing and are able to maintain this orientation after solidification due to their longer relaxation time. The characteristic of the LC polymers to maintain the molecular orientation in the solid state yields superior mechanical properties such as tensile modulus and strength. Moreover, TLC polymers show high softening and melting temperature due to their rod-like structure. This is why TLC polymers are prime candidates for high performance polymers and reinforcement of flexible polymers. 3 -7 Generally, the tensile strength of the TLC polymers strongly depends on the molecular structure, molecular orientation, processing conditions, and heat treatment. A number of studies 8 -12 have been reported on the effect of processing condition, molecular orientation, and heat treatment on the mechanical properties of TLC polymers, but there are few studies on the relationship between molecular structure and mechanical properties of TLC polymers. The present article describes the effect of the rigid units content on tensile properties of new TLC polyesteramides controlled the rigid units content and obtain some detailed information about the relationship between molecular structure, molecular orientation and tensile properties. The difference in tensile properties was interpreted in terms of the molecular orientation an...

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Solid-state CP/MAS carbon-13 NMR study of thermotropic aromatic polyester containing a flexible spacer in the main chain

Cited by 31 publications

References 14 publications

Preparation and Properties of Polyurethanes Containing Mesogenic Units

Preparation and Properties of Polyurethanes Containing Mesogenic Units

Synthesis and Solid-State Polymerization of Liquid-Crystalline Acrylic Monomers Containing Chiral Epoxy Groups

Effect of the Rigid Units Content on Tensile Properties of the Thermotropic Liquid Crystalline Polyesteramides

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