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  • 1
    Electronic Resource
    Electronic Resource
    Preparation and thermotropic properties of copoly(4,4′-biphenylene sebacate-co-eicosanedioate)s (1992)
    Springer
    Polymer bulletin 28 (1992), S. 539-545 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A series of thermotropic copoly(4,4′-biphenylene sebacate-co-eicosanedioate)s were prepared by melt polycondensation of 4,4′-biphenylene diacetate, sebacic acid and eicosanedioic acid. Their thermal transitions and liquid crystalline properties were investigated by DSC and polarized micrrocope. The copolyesters were found to exhibit a smectic phase, but no nematic phase was observed upon cooling. The smectic-isotropic transition temperature decreased as the content of eicosanedioate unit increased, and the corresponding transition heat did not change to a great extent. However, the crystalline-smectic transition temperature showed an eutectic behavior, and the crystalline-smectic transition heat was depressed considerably after copolymerization. The X-ray diffraction data of the copolyesters after thermal treatment were measured and compared with the thermal properties measured by DSC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296044
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  • 2
    Electronic Resource
    Electronic Resource
    Thermotropic copolyesters modified with nonmesogenic rigid groups (1990)
    Springer
    Polymer bulletin 23 (1990), S. 647-651 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Two series of copolyesters of sebacic acid, 4,4′-biphenol and a nonmesogenic rigid diol which was either bisphenol A (BPA series) or hydroquinone (HQ series) were prepared by melt polycondensation. The thermal transitions and melt birefringence which were investigated by DSC and polarized microscope respectively. Homopolyester of 4,4-biphenol and sebacic acid (PB8) was found to show two transition temperatures corresponded to Tm and Ti respectively. For the BPA series, the incorporation of amorphous bisphenol A unit by copolymerization decreased both Tm and Ti and completely destroyed the mesophase as the content of bisphenol A unit was over 50 mole%. For the HQ series, the incorporation of crystalline hydroquinone unit decreased Tm to more extent, but decreased Ti to less extent as compared to the BPA series. When the hydroquinone unit was as high as 80 mole%, the mesophase was completely destroyed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01033112
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  • 3
    Electronic Resource
    Electronic Resource
    Thermotropic copolyesters modified with nonmesogenic rigid groups (1990)
    Springer
    Polymer bulletin 24 (1990), S. 293-297 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Two series of copolyesters of sebacic acid, 4,4′-biphenol and a nonmesogenic rigid diol which was either bisphenol A (BPA series) or hydroquinone (HQ series) were prepared by melt polycondensation. The thermal transitions and melt birefringence which were investigated by DSC and polarized microscope respectively. Homopolyester of 4,4-biphenol and sebacic acid (PB8) was found to show two transition temperatures corresponded to Tm and Ti respectively. For the BPA series, the incorporation of amorphous bisphenol A unit by copolymerization decreased both Tm and Ti and completely destroyed the mesophase as the content of bisphenol A unit was over 50 mole%. For the HQ series, the incorporation of crystalline hydroquinone unit decreased Tm to more extent, but decreased Ti to less extent as compared to the BPA series. When the hydroquinone unit was as high as 80 mole%, the mesophase was completely destroyed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00306577
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  • 4
    Electronic Resource
    Electronic Resource
    Copolyesters (1991)
    Springer
    Polymer bulletin 27 (1991), S. 141-146 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary In an attempt to prepare the block copolyesters of poly (butylene terephthalate) (PBT) and poly(butylene adipate) (PBA), melt transesterification between PBT and PBA was chosen first. However, PBT and PBA were found to be immiscible within the reaction temperature range. This hindered their transesterifi-cation reaction. Various parameters such as catalyst, reaction temperature, reaction time, degree of vacuum and stirring speed all failed in preparing the block copolyesters of PBT and PBA. However, when some amount of 1,4-butanediol was added at the melt mixing stage, followed by a vacuum stage at high temperature, block copolyesters could be prepared. The chemical structure and thermal properties of the block copolyesters were characterized by NMR and DSC respectively. As the degree of randomness of the block copolyesters increased, the melt transition temperature of PBT segment decreased, and that of PBA segment decreased considerably. When, the degree of randomness reached as high as 0.35, the melt transition of PBA segment disappeared.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296023
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  • 5
    Electronic Resource
    Electronic Resource
    Block copolyetheresters (1995)
    Springer
    Polymer bulletin 35 (1995), S. 743-749 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Block copolyetheresters with hard segments of poly (pentamethylene p,p'-bibenzoate) and soft segments of poly (tetramethylene ether) have been prepared by melt polycondensation of dimethyl p,p'-bibenzoate, 1,5-pentanediol and poly(tetramethylene ether) glycol (PTMEG) with molecular weights of 650, 1000 and 2000. The polymer composition is governed by the charge molar ratio (x) of PTMEG to dimethyl p,p'-bibenzoate. The block copolyetheresters with x=0.05, 0.1 and 0.2 display a monotropic smectic phase due to the poly (pentamethylene p,p'-bibenzoate) segments. But the block copolyetheresters with x=0.3 exhibit no liquid crystalline behavior. The molecular weight of the PTMEG used has significant effect on the glass transition temperature and crystallizability of the polyether segments. It can be seen from the glass transition temperature results that the miscibility between amorphous parts of the polyether segments and those of the polyester segments is also dependent on the molecular weight of the PTMEG used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00294958
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  • 6
    Electronic Resource
    Electronic Resource
    Crystallization kinetics of two polyesters with different main chain rigidity (1997)
    Springer
    Journal of polymer research 4 (1997), S. 129-133 
    Details
    ISSN: 1572-8935
    Keywords: Crystallization kinetics ; Polyesters ; Avrami plot ; Nucleation ; Growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The crystallization kinetics of two polyesters, poly(p-phenylene sebacate) (PPS) and poly(p-phenylene isophthalate) (PPI), have been investigated by DSC. The nonisothermal data indicate that the relative crystallization rate of PPI was slower than that of PPS due to the more rigid nature of the PPI the chains. The isothermal crystallization data were analyzed by the Avrami equation, 1 − X(t) = exp(−ktn). PPS exhibited Avrami exponent (n), values of about 4, indicating that its isothermal crystallization followed a process of homogeneous nucleation, spherical growth and a growth type of interface control. PPI exhibited Avrami exponent values of about 3 indicating its isothermal crystallization followed a process of homogeneous nucleation, a possible disc growth geometry and an interface control growth type. Possibly, the bending structure and rigid nature of PPI forced its growth to follow a three dimensional growth during crystallization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s10965-006-0016-0
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of molecular weight on two smectic polyesters (1996)
    Springer
    Journal of polymer research 3 (1996), S. 59-63 
    Details
    ISSN: 1572-8935
    Keywords: Thermotropic ; Liquid crystalline polymers ; Smectic ; Intrinsic viscosity ; Thermal transitions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The liquid crystalline transitions of two kinds of smectic polyesters with different molecular weights were investigated by DSC, polarized microscopy and X-ray diffraction. The molecular weight affects the transitions significantly for these two kinds of polyesters. With a high enough molecular weight, both poly (pentamethylenep,p′-bibenzoate) and poly(hexamethylenep,p′-bibenzoate) exhibit an enantiotropic smectic phase, but the two endothermic transition peaks of the DSC heating curve seem to overlap. The polyesters tend to exhibit a monotropic smectic phase as the molecular weight decreases. From the DSC cooling curve, the isotropic-smectic transition can be seen more clearly. As the molecular weight decreases, the smectic order decrease significantly. The molecular weight affects the transitions in a different way for these two different kinds of polyesters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01493381
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  • 8
    Electronic Resource
    Electronic Resource
    Phase separation in segmented polyurethanes derived from mixtures of polyether polyols with different functionality (1996)
    Springer
    Journal of polymer research 3 (1996), S. 221-225 
    Details
    ISSN: 1572-8935
    Keywords: Segmented polyurethanes ; Phase separation ; Compatibility ; Polyol mixture ; Thermal transitions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A series of segmented polyurethanes containing 60 wt° of hard segments (HS) was prepared from MDI (4,4′-diphenylmethane diisocyanate) ethylene glycol and mixtures of a polyoxyethylene end-capped polyoxypropylene triol and a polyoxyethylene end-capped polyoxypropylene diol. The effects of the content of polyether diol in polyether polyols on phase separation and properties was investigated by dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and investigation of tensile properties. The DSC and DMA results indicate that the polyurethane derived from only polyether triol exhibits obvious phase separation and that the HS is immiscible with the SS, but that the HS is compatible with the HS for the polyurethane derived from polyether diol. As the content of polyether diol increases, the compatibility between HS and SS increases. As the content of polyether diol increases, the tensile strength. elongation. toughness and tear resistance of the polyurethanes increases. but their moduli decrease. The modulus-temperature dependence in the temperature region of −30 to 65 °C increases as the polyether diol content increases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01493491
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis and thermal properties of block copolyetheresters with poly(pentamethylene p,p′-bibenzoate) segments (1995)
    Springer
    Journal of polymer research 2 (1995), S. 109-114 
    Details
    ISSN: 1572-8935
    Keywords: Thermotropic ; Liquid crystalline polymers ; Smectic ; Block copolyetheresters ; Thermal transitions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The block copolyetheresters with hard segments of poly(pentamethylene p,p′-bibenzoate) and soft segments of poly (tetramethylene ether) were prepared by melt polycondensation of dimethyl-p,p′-bibenzoate, 1,5-pentanediol and poly (tetramethyene ether) glycol (PTMEG) with molecular weights of 650, 1000 and 2000. The results by NMR indicate that the polymer composition is determined by the charge molar ratio (x) of PTMEG to dimethyl-p,p′-bibenzoate. The thermal transitions of the block copolyetheresters were investigated by DSC in combination with X-ray diffraction and polarized microscopy. Some block copolyetheresters exhibit a monotropic smectic phase due to the presence of the poly (pentamethylene p,p′-bibenzoate) segments. As the molar content of PTMEG increases, the average sequence length of the polyester segments decreases, the isotropic-smectic transition temperature and the smectic order decrease accordingly. When x is as high as 0.3, the block copolyetheresters exhibit no liquid crystallinity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01493210
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  • 10
    Electronic Resource
    Electronic Resource
    Phase separation and phase inversion of polyurethane networks (1996)
    Springer
    Journal of polymer research 3 (1996), S. 159-163 
    Details
    ISSN: 1572-8935
    Keywords: Polyurethane networks ; Phase separation ; Phase inversion ; Thermal properties ; Mechanical properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A series of polyurethane networks were prepared from MDI (4,41-diphenyl methane diisocyanate), ethylene glycol and a polyoxyethylene-tipped polyoxypropylene triol. The phase separation and phase inversion phenomena of these polyurethane networks were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and measurement of their tensile properties. The DSC and DMA data indicate that the segmented copolyurethanes possess a two-phase morphology comprising soft and hard segments. It can be found from DSC data that the polyether soft segments exhibit a Tg (glass transition temperature) of −60 °C, and the aromatic hard segments display a Tg of about 128 °C. Two Tgs corresponding to the comprised segments can also be found by DMA for some segmented polyurethanes. Varying the content of aromatic hard segments over the range from 0 to 80 wt% changes the material behavior from a soft rubber through a highly extensible elastomer to a brittle semi-ductile glassy material. Based on the property-composition plots, phase inversion appears to occur at a hard segment content of about 50 wt%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01494525
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