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  • 1
    Electronic Resource
    Electronic Resource
    Structural changes and chain orientational behavior during tensile deformation of segmented polyurethanes (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 2085-2098 
    Details
    ISSN: 0887-6266
    Keywords: orientation ; polyurethane ; deformation ; orientation function ; hydrogen bond ; hard domain ; soft domain ; infrared dichroism ; relaxation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Structural changes and segmental orientation behavior of polyurethane have been studied during uniaxial deformation. The orientation function change of the two (free and hydrogen bonded C=O stretching peaks) peaks during a full cycle of deformation has been observed to be distinctively different. Even though the hydrogen-bonded C—O peaks showed hysteresis behavior, the free C—O peaks exhibited quite elastic behavior. It was thus concluded that the orientation behavior of free and hydrogen-bonded C—O stretching peak represents the deformation characteristics of soft and hard domains, respectively. The orientation behavior at different temperatures also has been studied. Temperature has a significant effect on the orientation behavior of the soft domain, whereas it has negligible effect on the hard domain orientation. It was also demonstrated that the structural change due to the deformation could be analyzed by infrared spectroscopy. Some of the hydrogen-bonded carbonyl groups have been observed to be transferred to the free carbonyl groups, indicating that a small amount of the hard segments in the hard domain have been pulled out into the soft matrix upon deformation. The orientational relaxation also has been studied as a function of time. The segmental relaxation of the hard segments appears to be quite characteristic depending on the nature of the domain in which they reside. © 1994 John Wiley & Sons, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1994.090321215
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of the steric hindrance on metallic cation conduction in polymer electrolytes (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 879-885 
    Details
    ISSN: 0887-624X
    Keywords: polyisocyanates ; polymer electrolytes ; metallic cation conducting polymers ; steric hindered phenols ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,6-Di-t-butylphenol and oligo(ethylene oxide) bound covalently to polyisocyanate were synthesized and characterized. The ionic conductivities of their Li, Na, and K phenolates were studied at various temperatures. The conductivities were in the range of 10-7-10-5 S/cm at 30°C. The conductivity of Na and K salts was approximately 102 greater than that of the Li salts. The t-butyl groups serve to dissociate K and Na ions from the phenoxide. The cations, therefore, are more mobile as a result increasing the conductivity. The temperature dependence of ionic conductivity suggests that the migration of ions is controlled by segmental motion of the polymer, shown by linear curves obtained in Vogel-Tammann-Fulchere plots. The polyisocyanate backbone is a rather stiff structure, however, a flexible oligo(ethylene oxide) side chain forms complexes with metal ion. Since the ion transport is associated with the local movement of polymer segments, the rigidity of the polymer backbone does not have much influence on the ion mobility.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080300519
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  • 3
    Electronic Resource
    Electronic Resource
    Alkali metal ion conductors based on sulfonated poly(p-phenylene terephthalamide) (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 3009-3017 
    Details
    ISSN: 0887-624X
    Keywords: Na ; Li poly(phenylene terephthalamide sulfonate salts) ion conductivity ; modified ethylene carbonate ; blend system ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To obtain thermally stable and mechanically strong sodium and lithium conducting polymers, we prepared Na+ and Li+ poly(phenylene terephthalamide sulfonate salts) (MW ∼ 5500). We also synthesized oligo(ethylene oxide) (3, 5, or 7 units of ethylene oxide) substituted ethylene carbonate and poly[oxymethylene-oligo(oxyethylene)]. These are high boiling point liquids with high dielectric constants as well as metal chelating properties. Polyelectrolyte systems were prepared by mixing Na+ or Li+ poly(phenylene terephthalamide sulfonate) salts with various amounts of modified ethylene carbonate and/or poly[oxymethylene-oligo(oxyethylene)]. Films (0.1-0.5 mm thick) obtained from the blends were found to have considerable mechanical strength; forming free standing films. The ionic conductivities of the Na+ and Li+ polyelectrolyte systems were 10-6-10-5 S/cm at 25°C. Thermal properties of these blend systems were investigated in detail. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080321602
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  • 4
    Electronic Resource
    Electronic Resource
    Design of alkaline metal ion conducting polymer electrolytes (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 2573-2581 
    Details
    ISSN: 0887-624X
    Keywords: single alkaline metal ion conductors ; polymer electrolytes ; antioxidation properties ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polysiloxanes with covalently attached oligo ethylene oxide and di-t-butylphenol (I), naphthol (II), and hexafluoropropanol (III) were synthesized. The crosslinked polymers with a hexamethylene spacer were also prepared. The ion conductivities of the Li, Na, and K salts were measured as a function of temperature. The highest conductivities for K and Na of I at 30°C were 5.5 × 10-5 and 5.0 × 10-5 S/cm, respectively, when the ratio of the ion to ethylene oxide unit was 0.014. On the other hand, Li conductivity was 8.0 × 10-6 S/cm when the ratio between Li and ethylene oxide unit was 0.019. The maximum conductivities of Li ions of II and III were in the order of 10-6 and 10-7 S/cm at 30°C, respectively. When the polymers were crosslinked by a hexamethylene residue, the ion conductivities decreased while the degree of crosslinking increased. The temperature dependence of the cation conductivities of these systems could be described by the Williams-Landel-Ferry (WLF) and the Vogel-Tammann-Fulcher (VTF) equation. The results demonstrate that ion movement in these polymers is correlated with the polymer segmental motion. The order of ionic conductivity was K+ 〉 Na+ ≫ Li+. This suggests that steric hindrance and π-electron delocalization of the anions attached to polymer backbone have a large effect on ion-pair separation and their ionic conductivities. Thermogravimetric analysis of the polymers indicated that the degradation temperature for I and II were about 100°C higher than for poly(siloxane-g-ethylene oxide). This is due to the antioxidant properties of sterically hindered phenols and naphthols. © 1993 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080311018
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  • 5
    Electronic Resource
    Electronic Resource
    Quinone-modified polymers as electron transfer relay systems in amperometric glucose sensors (1991)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 2 (1991), S. 229-235 
    Details
    ISSN: 1042-7147
    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
    Notes: A polysiloxane and an acrylonitrile-ethylene copolymer with covalently attached p-hydroquinone/benzoquinone moieties were prepared and tested as electron transfer relay systems in amperometric glucose biosensors. Using experiments involving cyclic voltammetry and stationary potential measurements, it was shown that the polysiloxane relay system can efficiently mediate electron transfer from reduced glucose oxidase to a conventional carbon-paste electrode. Sensors containing this polymeric relay system and glucose oxidase respond rapidly to low (〈0.1 mm) glucose concentrations, with steady state current responses achieved in less than 1 min. The acrylonitrile-ethylene copolymer was found to be less efficient than the polysiloxane system at mediating the electron transfer from reduced glucose oxidase to the electrode. The dependence of the sensor response on the nature of the polymer backbone is discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1991.220020504
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  • 6
    Electronic Resource
    Electronic Resource
    Amperometric enzyme-modified electrodes based on tetrathiafulvalene derivatives for the determination of glucoseThis paper is dedicated to Professor Herbert C. Brown on the occasion of his 80th birthday. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 3 (1992), S. 303-310 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of tetrathiafulvalene (TTF) derivatives have been synthesized and tested as electron transfer mediators in glucose oxidase-based amperometric biosensors. Using cyclic voltammetry and stationary potential experiments, it is shown that several of these derivatives can effectively mediate electron transfer from the reduced flavin adenine dinucleotide redox centers of glucose oxidase to a conventional carbon paste electrode. An insoluble polymeric electron relay system, based on the covalent attachment of TTF moieties to a highly flexible siloxane polymer, is also shown to facilitate a flow of electrons from the enzyme to the electrode. The resulting glucose biosensors function efficiently over a clinically relevant range of glucose concentrations.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hc.520030316
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  • 7
    Electronic Resource
    Electronic Resource
    Rheological study on poly-D(-)(3-hydroxybutyrate) and its blends with poly(ethylene oxide) (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 1636-1642 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Aspects of thermal, morphological, and rheological properties of biodegradable poly-D(-)(3-hydeoxybutyrate) (PHB) blended with poly(ethylene oxide) (PEO) have been studied. Thermal properties and morphology of the blends were examined by scanning electron microscopy and differential scanning calorimetry, respectively. A rotational theometer with parallel plate geometry was also adopted to investigate the rheological properties of these blends. In addition, dynamic ciscoelasticity was measured by a Rheovibron as functions of time and temperature. From these measurements, PHB and PEO were observed to be miscible in the melt state. In the case of the blend systen 80/20 PHB/PEO by weight, the vacant domains of the PHB were filled with PEO particles, and this morphological state enhanced the rheological properties. Furthermore, PHB and its blends were found to have high crystallinities, but to have unstable thermal behavior about Tm.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760352010
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