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  • Chemistry  (20)
  • Computer Systems
  • 1990-1994  (19)
  • 1935-1939  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 207 (1993), S. 9-21 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wird ein phänomenologisches Modell vorgestellt, mit dem sich das Entstehen starker Anisotropien der physikalischen Eigenschaften semikristalliner Polymerer nach einachsigem Verstrecken beschreiben 1äßt. Dieses Modell führt die Temperatur als expliziten Parameter in die Orientierungsfunktion ein. Es enthält zwei frei wählbare Parameter, die für jedes Polymere durch Anpassen der experimentellen Daten der Doppelbrechung als Funktion des Verstreckverhältnisses bei einer bestimmten Temperatur ermittelt werden konnen. Die berechneten Werte für Elastizitätsmodul, thermische Leitfähigkeit und Expansibilität parallel und senkrecht zur Streckrichtung stimmen in einem wäiten Bereich des Verstreckverhältnisses und der Temperatur mit den experimentellen Ergebnissen gut überein.
    Notes: A phenomenological model has been proposed to understand the development of strong anisotropy in physical properties of semicrystalline polymers on uniaxial drawing. The proposed model introduces temperature as an explicit parameter in the orientation function. The model contains two free parameters for each polymer which can be evaluated by fitting the experimental data on birefringence versus draw ratio at a particular temperature. The calculated values of elastic moduli, thermal conductivity and expansibility along and perpendicular to the drawing direction over the entire range of draw ratio and a wide range of temperature are in good agreement with experimental values.
    Additional Material: 6 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 45 (1994), S. 182-187 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: X-ray diffraction has been used to determine the structure of the poly(p-phenylene 2,5-di-hexadecyloxy-terephthalate), which is one of a series of polyesters with stiff aromatic mainchains and flexible aliphatic sidechains currently being studied by this laboratory. The X-ray data for oriented melt quenched films show that this polymer adopts an interesting and novel structure, in which the backbones and sidechains form separate incommensurate lattices. The backbones are fully extended, and adopt a monoclinic structure with unit cell dimensions: a=26.2Å, b=7.3Å, c=12.6Å, and α=130°C. They are in contact along the b axis, thereby forming stable sheets that are separated by intercalated, highly extended sidechains, which point along the a axis. The sidechains are packed in a columnar, approximately hexagonal structure that is similar to the hexagonal form of linear alkanes. The repeat for the sidechain lattice along the backbone direction is c=13.2Å, and thus the two lattices are incommensurate. We envisage a small disordered boundary layer between the backbone and sidechain lattices, containing some of the inital and final carbons of the sidechain, and accommodating any conformational isomerism. This allows an independent lattice to be formed by the central sections of the sidechains, but this cannot propagate indefinitely because of the different c dimension and the restrictions imposed by covalent linkage to the backbones. As a result, the sidechain crystallites are only approximately 50Å wide, compared to approximately 200Å for those formed by the backbones. Simulated X-ray patterns for the above incommensurate structure show good qualitative agreement with the observed data.
    Additional Material: 6 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 1685-1692 
    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 group of poly(N-vinylcarbazole) pendant polysulfones has been prepared by reacting it with benzene, toluene, p-chlorobenzene- and p-nitrobenzenesulfonyl chloride and N-methyl carbazole, 3,6-disulfonyl chloride by the Friedel Crafts reaction. Carbazole-based backbone polysulfones have also been prepared by the reaction of N-methyl carbazole, 3,6-disulfonyl chloride and biphenyl, naphthalene, anthracene, and carbazole in presence of anhydrous aluminum chloride. The various sulfone polymers, thus prepared, have been structurally characterized by elemental analysis and IR spectroscopy. Detailed analyses of thermal stability, dielectric, and conductivity characteristics have revealed certain significant differences between these two types of sulfone polymers.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 40 (1990), S. 1703-1710 
    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: PVC modified by Cl displacement reaction with meta-aminophenol (MAP), bisphenol A (BISA), and phenolphthalein (PHEN) has been converted into phosphoric acid cation exchange resins. These resins have been characterized in regard to their structure, ion exchange properties, and thermal stability. The ion exchange capacities fall into the range 5.5-8.0 (meq/g) for the resins. The overall thermal stability is considerably higher than that for the corresponding sulfonic acid resins, as well as for the PVC-MAP, PVC-BIS A, and PVC-PHEN condensates. The resins exhibit ca. 4-6% capacity losses under isothermal hydrolytic cleavage at 100°C for 24 h.
    Additional Material: 3 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 619-621 
    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: Friedel-Crafts acylation reaction between polystyrene and phthalic anhydride in the presence of AlCl3 has been performed in two different solvents, 1,2-dichloro ethane and nitro-benzene. The morphology of the condensate prepared in 1,2-dichloroethane has revealed the participation of 1,2-dichloroethane, i.e., a competitive Friedel-Crafts alkylation reaction.
    Additional Material: 4 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 1989-1995 
    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: Copolycondensates have been prepared from carbazole, poly(N-vinylcarbazole) and various aromatic anhydrides, e.g., phthalic anhydride, trimellitic acid anhydride, pyromellitic dianhydride, naphthalene tetracarboxylic dianhydride, and benzophenone tetracarboxylic dianhydride in presence of the Friedel-Crafts catalyst anhydrous zinc chloride at high temperature. The polymers have been characterized by elemental analyses and IR spectroscopy. Thermal stabilities, dielectric, and conductivity behaviors of these polymers have also been evaluated and it has been observed that these properties show interesting differences depending upon the nature of the anhydride.
    Additional Material: 4 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 2489-2498 
    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: Anthracene-mono- and disulfonyl derivatives of polystyrene and poly (N-vinylcarbazole) have been prepared and the thermal stability, dielectric, and conductivity of these polymer pendant sulfones have been evaluated. The anthracene-based benzene, naphthalene, anthracene, and biphenyl copolysulfones have also been prepared and characterized in regard to the above-cited properties. Interesting variations in these properties between these two classes of polymers carrying pendant and backbone sulfonyl groups have been noted and rationalised from structural considerations.
    Additional Material: 7 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 3795-3800 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 3 (1992), S. 257-262 
    ISSN: 1042-7147
    Keywords: Chiral liquid crystalline polymers ; Antiferroelectricity ; Ferrielectricity ; SAXS ; 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: The structure and phase behavior of liquid crystalline polymers (LCPs) having a common chiral side chain mesogen but different main chain structures have been investigated using small-angle X-ray scattering (SAXS). While the low molecular weight chiral side chain mesogen by itself exhibits ferroelectricity, the SAXS data of the side chain LCP with a flexible polyacrylate backbone contains a bilayered superstructure peak that is indicative of antiferroelectric order. The combined LCP with a nonpolar main chain mesogen also has a bilayered superstructure, but has a different structural organization in the proposed antiferroelectric phase compared to the side chain LCP. Further changes in the phase behavior and structural organization occur when a polar group is introduced into the main chain mesogen. A ferrielectric phase has been proposed to explain the observation of a trilayered superstructure in the corresponding SAXS data. The influence of the chemical structure and connectivity on the phase behavior and superstructure formation in the chiral LCPs is discussed.
    Additional Material: 5 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 1453-1460 
    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: Polystyrene-divinylbenzene (PS-DVB) copolymer was modified by anchoring dipyridylamine (DPA) on it followed by complexation with Fe(III). Under the experimental conditions followed, 9% incorporation of Fe(III) was achieved. PS-DVB-DPA and PS-DVB-DPA-Fe(III) were characterized by IR spectra. Diffuse reflectance spectra for PS-DVB-DPA-Fe(III) and DPA-Fe(III) revealed λmax at ∼ 360 and ∼ 310, respectively. This difference could be due to a difference in the nature of the coordinating moieties complexing with Fe(III) in these two systems. Scanning electron micrographs of PS-DVB, PS-DVB-DPA-Fe(III), and heat-treated PS-DVB-DPA-Fe(III) revealed some typical surface features. Thermal stability varied in the order PS-DVB-DPA-Fe(III) 〉 PS-DVB-DPA ≅PS-DVB, and DTA showed characteristic exotherms. © 1992 John Wiley & Sons, Inc.
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