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  • 1
    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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  • 2
    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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  • 3
    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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  • 4
    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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  • 5
    Electronic Resource
    Electronic Resource
    Elasticity behavior of swollen polyurethane networks (1999)
    Springer
    Journal of polymer research 6 (1999), S. 117-122 
    Details
    ISSN: 1572-8935
    Keywords: Polyurethane networks ; Solution behavior ; Gaussian behavior ; Flory-Huggins equation ; Interaction parameter
    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 by reacting MDI (4,4′-diphenylmethane diisocyanate) with various mixtures of poly(oxyethylene) end-capped poly(oxypropylene) triol and diol. The uniaxial compressive properties of the polyurethane networks both in equilibrium swelling in toluene and in a dried state were measured at 27 °C. The compressive stress-strain data were analyzed according to equations based on the Gaussian theory of elasticity. Deviations from the Gaussian behavior were observed; however, as the polyether diol content increased, deviations from the Gaussian behavior decreased. The interaction parameters between the polyurethane networks and toluene at an equilibrium state were analyzed by the Flory-Huggins equation. As the polyether diol content increased, the interaction parameter, χ, increased due to the increasing content of the poly(oxyethylene) unit and urethane group concentration. With increasing polyether diol content, polyurethane networks approached phantom behavior more closely.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s10965-006-0078-z
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  • 6
    Electronic Resource
    Electronic Resource
    Block copolyetheresters. V. Low-temperature properties of thermotropic block copolyetheresters (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 59 (1996), S. 1027-1031 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The low-temperature properties of block copolyetheresters with hard segments of poly(alkylene p,p′-bibenzoate) and soft segments of poly(tetramethylene ether) were investigated by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). In the temperature range of -100 to 60°C, two transition temperatures, a glass transition temperature (Tg) and a melting temperature (Tm), were found by DSC and are attributed to the polyether segments. The Tg monitored by DSC of the polyether segments of the block copolyetheresters is around -68°C and independent of the composition and the type of polyester segment. Thus, the amorphous parts of the polyether segments should be immiscible with the amorphous parts of the polyester segments. The polyether segments of the block copolyetheresters exhibit a lower Tm and a lower crystallinity than those of the poly(tetramethylene ether)glycol due to the presence of the polyester segments. The crystallizability of the polyether segments is dependent on the composition to some extent. The DMA data show that the dynamic modulus drops more abruptly around -10 to 15°C, indicating that the mechanical properties may change significantly due to the melting of the polyether segments. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 7
    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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    Paper (German National Licenses)
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