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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 33 (1994), S. 1-8 
    ISSN: 0959-8103
    Keywords: network polyester films ; glycerol ; aromatic and aliphatic dicarboxylic acids ; soluble prepolymers ; ordered network structure ; degree of reaction ; heat distortion temperature ; 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: This paper presents information on the preparation of the network polyester films from glycerol (Yg) and aromatic dicarboxylic acids of phthalic anhydride (P), dimethyl isophthalate (I) and dimethyl terephthalate (T), as well as aliphatic dicarboxylic acids of adipic, sebacic, 1, 10-decanedicarboxylic and 1, 12-dodecanedicarboxylic acids, and their properties. Yg and dicarboxylic acid were polycondensed immediately before the gelation started. The prepolymers obtained were cast from DMF solution and successively post-polymerized at various temperatures and times to form networks. The resultant films were transparent, flexible and insoluble in organic solvents. Heat distortion temperature (Th) measured by a penetration mode of thermomechanical analysis increased with increasing post-polymerization temperature and time, and then leveled out. Th values corresponded well to the glass transition temperature (Tg) measured by differential thermal analysis (DTA). Th was 152°C, 162°C and 197°C for YgP, YgI and Yg T post-polymerized at 270°C for 6 h, respectively. Th values of network films made from aliphatic dicarboxylic acids could not be observed until complete probe penetration occurs, as a result of thermal decomposition because the Tg is lower than room temperature. The degree of reaction estimated from the IR absorbance of hydroxyl and methylene groups was in the range of 60-80%. Two diffraction peaks appeared in the wide-angle X-ray scattering pattern, suggesting some ordered structure owing to the regular networks. Density decreased with increasing post-polymerization time and temperature, in the order YgP 〉 YgI 〉 YgT. Network films made from aliphatic dicarboxylic acids had much lower tensile strength and Young's modulus, and greater elongation, than those made from dicarboxylic acids, as a result of the Tg being below room temperature.
    Additional Material: 10 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 33 (1994), S. 9-17 
    ISSN: 0959-8103
    Keywords: Polyacrylonitrile ; infrared dichroism ; orientation factors ; X-ray ; laterally-ordering ; solvent orientation ; dipole pairing ; 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: Polyacrylonitrile (PAN) films were made by casting a dimethyl sulphoxide (DMSO) solution. After drying, the films were uniaxially drawn by an essentially solid-state drawing procedure. Using polarised-infrared (IR) spectroscopy, the dichroism of the nitrile-stretching vibration was monitored as a function of draw ratio. The dichroism results were converted to plots of chain-orientation factor versus draw ratio. For this, α, the transition-moment angle of the vibration, has to be known. Though a value of 68-73° has been suggested in the literature, for the present samples α cannot be 70° or less, and 73° is the most appropriate. The meaning and nature of the transition-moment angle in the context of a flexible-chain polymer molecule is discussed. The IR spectrum also showed dichroism in the S=O stretch and the —CH3 rocking vibrations from the (residual) DMSO present in the film, indicating that the solvent molecules were also orientated. It is proposed that this occurred due to dipolar interactions between the S=O and the C≡N groups, which led to solvent molecules being bound to the polymer chains. X-ray diffraction studies indicated ‘lateral-ordering’ consisting of hexagonally packed, rod-like chains with no c-axis order. The diffraction patterns obtained here were the ‘standard’ ones for PAN, in contrast to those observed previously in solvent-containing PAN gels.
    Additional Material: 6 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 33 (1994), S. 37-41 
    ISSN: 0959-8103
    Keywords: poly(DL-lactic acid) ; poly(L-lactic acid) ; poly(D-lactic acid) ; stereocomplex ; degradation ; hydrolysis ; crystallisation ; morphology ; 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: Hydrolytic degradation of intrinsically amorphous poly(DL-lactic acid) was re-examined in pH 7.4 isoosmolar phosphate buffer at 37°C. Size-exclusion chromatogarphy, X-ray scattering and differential scanning calorimetry were used to monitor molecular weight and morphology changes up to the ultimate degradation stage. It was found that heterogeneous degradation of poly(DL-lactic acid) yielded a crystalline residual material of low molecular weight. Comparison with a stereocomplex made of equimolar poly(L-lactic acid) and poly(D-lactic acid) showed that the poly(DL-lactic acid) degradation residue was actually an oligomeric stereocomplex. The formation of stereoregular oligomeric enantiomers agreed well with the predominantly isotactic structure of poly(DL-lactic acid) obtained by ring-opening polymerization of DL-lactide and argued in favour of the stereodependence of main chain ester bond cleavage.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 33 (1994), S. 19-23 
    ISSN: 0959-8103
    Keywords: poly(1,4-phenylene sulphide) ; copper(I) 4-bromobenzenethiolate ; debromination ; polymerisation ; molar mass ; high-temperature viscometry ; 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: Debromination of poly(1,4-phenylene sulphide), PPS, chains during formation by solution polymerisation of copper(I) 4-bromobenzenethiolate, CBT, in quinoline and quinoline/pyridine mixtures at temperatures in the range 180-225°C has been investigated. The results are consistent with previously-reported model compound studies and show that debromination is insignificant if the polymerisation temperatures is ≤ 200°C. Pyridine was shown not to be essential for the formation of high molar mass PPS. The optimum conditions for preparing high molar mass PPS in high yield with no significant debromination were polymerisation of CBT at a concentration of 1.0 mol dm-3 in dry quinoline under a flowing dry nitrogen atmosphere at a controlled temperature of 200°C for about 24 h.
    Additional Material: 5 Tab.
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  • 5
    ISSN: 0959-8103
    Keywords: optical activity ; solid-state measurements ; natural polymers ; suspension ; birefringence ; isorefractive media ; 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 optical activity of ten natural-type polymers [poly(α-aminoacids), polysaccharides, proteins and nucleic acids] was measured in solution, as solid powders in suspension, and where possible in the form of films. In some cases the specific rotation of powder samples showed significant differences to the values obtained from solution measurements. The discrepances seem to reflect the arrangements of polymer chains in supermolecular assemblies in the polymer solid state.
    Additional Material: 11 Ill.
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  • 6
    ISSN: 0959-8103
    Keywords: latex ; polybutadiene ; sedimentation field-flow fractionation ; electron microscopy ; 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: A procedure based on sedimentation field-flow fractionation for physical characterization of polydisperse latexes is presented. The particle density, dimensions, polydispersity, size distribution and aggregation can be determined for both narrow and wide polydispersities. The procedure is applied to the sample case of polybutadiene latexes with density lower than water. The results are compared with independent measurements obtained by electron microscopy. The relevance of significant steps of the procedure, such as the nonequilibrium corrections, are discussed.
    Additional Material: 9 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 33 (1994), S. 43-60 
    ISSN: 0959-8103
    Keywords: poly(diacetylene)s ; model compounds ; conjugated polyenynes ; infinite chain length ; 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 syntheses of polyenynes as model compounds for poly(diacetylene)s (PDAs) are described. Variation of properties (UV-VIS, Raman, NMR and bond geometries) as a function of the chain length was investigated. After extrapolation to infinite chain length these data were compared to those for PDAs. From UV-VIS spectra a value of λ = 551 nm (2.25 eV) was calculated corresponding to the electronic transition of a single polyenyne chain. This energy is located at the low energy end of a yellow PDA solution spectrum. From Raman scattering v(C≡C) = 2108-2128 cm-1 and v(C≡C) = 1505-1532 cm-1 were calculated after extrapolation. Similarly sp-C13C NMR data yielded a shift of δ = 100 ppm. These data are almost identical to data known for yellow PDA solutions. Bond geometries are almost identical to those of poly(diacetylene)s and theoretical data.
    Additional Material: 7 Ill.
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  • 8
    ISSN: 0959-8103
    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
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  • 9
    ISSN: 0959-8103
    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
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0959-8103
    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
    Type of Medium: Electronic Resource
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