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  • Polymer and Materials Science  (836)
  • 1985-1989  (836)
  • 1920-1924
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 30 (1985), S. 2009-2020 
    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 mechanical properties, tensile strength, and elongation were investigated for poly(vinyl chloride) (PVC) samples mixed with dioctylphthalate (DOP) at concentrations from 0 to 100 parts per hundred parts PVC at 23°C. It was found that the tensile strength decreased with the increase of concentration, and the elongation was increased until a concentration of 30 DOP content, and then decreased. This leads to the suggestion that intermolecular plasticization is dominant until 30 DOP content, while interstructural plasticization is prevailing for higher concentrations. The permittivity ε′ and the dielectric loss factor ε″ of the same samples have been measured in the frequency range 102-105 Hz at temperatures from 3 to 96°C. Results show that as the DOP content increases in PVC, the dielectric absorption becomes broader, and the glass transition temperature Tg is lowered. The magnitude of the loss peak decreases with an increase of DOP content to a minimum at concentrations from 40 to 60 DOP content. At higher concentrations the loss peak is increased and Tg is unaltered. Another absorption was observed at 100 Hz and at high temperatures, which was attributed to Maxwell-Wagner effect or direct current conductivity or both of them. It was found that the sample containing 40 parts DOP in 100 parts PVC possesses the best mechanical and electrical properties.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dipeptides of the aromatic fluorescent amino acid, pyrenylalanine, are studied using both stationary and transient fluorescence techniques. Since the conformational transitions of the peptide chain are slow compared to the decay of the pyrene excited state, both ground state conformations, adopted by the peptide, i.e., C5 and C7, can be monitored separately. Kinetic models are proposed to describe the molecular dynamics of the peptide chain as probed by the intramolecular excimer formation between both pyrene chromophores. These kinetic schemes explain the influence of solvent, chain chirality, main chain-side chain interactions, and nature of the protecting groups on the emission spectrum and the fluorescence decay profile of these model peptides. These schemes also provide a tool to calculate rate constants of conformational transitions and excimer formation. By comparing the kinetic and thermodynamic parameters of the various compounds, the influence of a structural modification on the molecular dynamics of the peptide chain is determined.
    Additional Material: 11 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 38 (1987), S. 291-293 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß des Molverhältnisses Phenol: Formaldehyd auf die Viskosität und den Feststoffanteil des Harzes wurde untersucht. Die Bedingungen zur Herstellung eines Resols mit hohem Feststoffanteil und niedriger ViskositäUt werden aufgezeigt.
    Notes: The effect of the molar ratio phenol: formaldehyde on the viscosity and the solid content of the resin has been investigated. The conditions for preparation of a resole with high solid content and low viscosity are studied
    Additional Material: 4 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 2529-2535 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aqueous pseudoheterogeneous polymerization of methyl methacrylate in the absence and presence of some metal chlorides or sulfates was carried out in nitrogen atmosphere at 40°C using sodium bisulfite as initiator. The metal chlorides or sulfates were found to catalyze the rate of polymerization of methyl methacrylate to different extents. The highest effect was obtained in the presence of copper salts, a moderate effect was obtained when iron salts were used, and the least effect was caused by the others. All 13C-NMR spectra for the polymers obtained in the absence and presence of some metal salts were those to be expected for radically initiated poly(methyl methacrylate)s of conventional, slightly syndiotactic-rich microstructures prepared at normal temperature. The spectra were found to be very similar to that for a radical poly(methyl methacrylate) first analyzed by Inoue et al. The ratios of isotactic (mm): heterotactic (mr,rm): syndiotactic (rr) triads were found to be close to 6 : 32 : 62. The polydispersity for some poly(methyl methacrylate)s determined by gel permeation chromatography technique was found here to vary rather widely and ranges between 1.8 and 8.92.
    Additional Material: 6 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 26 (1988), S. 17-24 
    ISSN: 0887-6258
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
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  • 6
    ISSN: 0887-6258
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 1285-1294 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of electrically conducting pyrrole “black” polymers has been prepared by chemical oxidation of pyrrole with a variety of ferric salts. The synthesis and properties of these materials are described and compared with electrochemically-prepared analogs. Pyrrole “blacks” with strong acid anion “dopants” exhibited the highest conductivities, up to 62 Ω cm-1 for the triflate-doped polymer. The adjustability and ease of synthesis of the ferric-derived polypyrroles render these particularly promising for large-scale processing of conducting polymers.
    Additional Material: 2 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 3145-3149 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 31 (1986), S. 1509-1514 
    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 reactivity ratios for 2-isopropenyl-2-oxazoline (IPO), a dual functional monomer, have been determined using a combination of gas chromatography, with an internal standard, and a new form of the integrated copolymerization equation. The results indicate a parallel trend with the reactivity ratios of styrene in spite of the large disparity in polarity between IPO and styrene.
    Additional Material: 4 Tab.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 2333-2344 
    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: A simple, activity-based solution model is used to develop thermodynamically proper correlation forms for the description of the rate and equilibrium behavior of nonideal polyamidations. The approach is especially useful in systems for which limited equilibrium and kinetic data are available. This model is applied to the nylon 6,6 system. the resulting correlation is valid for water concentrations from 1 to 90 mol% and for temperatures from 200 to 265°C. The equilibrium correlation is a function of the water mole fraction and temperature. At a fixed temperature, there is a maximum in the apparent equilibrium constant at a water concentration of approximately 10 mol%. There is an apparent inversion in the sign of the heat of amidation, as well as a continuous change in the apparent rate of polymerization from second to third order in carboxyl concentration at low water content.
    Additional Material: 7 Ill.
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