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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of polymers and the environment 3 (1995), S. 215-223 
    ISSN: 1572-8900
    Keywords: Copolyesters ; biodegradability ; aliphatic diol ; adipic acid ; terephthalic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Copolyesters composed of aliphatic and aromatic compounds were synthesized by the polycondensation of 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, sebacic acid, adipic acid, and terephthalic acid. By applying an appropriate ratio of aliphatic to aromatic acids, the synthesized materials proved to be biodegradable, as was verified by several degradation test methods such as aqueous polymer suspension inoculated by a soil eluate (Sturm test), a soil burial test (at ambient temperature), and a composting simulation test at 60°C. The degradability of the polyester-copolymers (measured as weight loss) was investigated with respect to the aliphatic monomer components and the fraction of terephthalic acid. Excellent biodegradability was observed even for copolymers with a content of terephthalic acid up to 56 mol% (of the acid fraction) and melting points in the range up to 140°C. Degradation by chemical hydrolysis of the polyesters was determined independently and was found to facilitate microbial attack significantly only at higher temperatures. The findings demonstrate that biodegradable polymers with advantageous usage properties can easily be manufactured by conventional techniques from commodity chemicals (adipic acid, terephthalic acid, and ethylene glycol or 1,4-butanediol).
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-5028
    Keywords: nuclear-mitochondrial interaction ; mitochondrial malate dehydrogenase ; Brassica napus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two-dimensional analyses of mitochondrial proteins of Brassica napus revealed a set of differences in patterns of mitochondrial matrix proteins isolated from different nuclear backgrounds. One of these varying proteins was identified as mitochondrial malate dehydrogenase (mMDH; EC 1.1.1.37) by homology analyses of the partial amino acid sequence. Immunological detection identified additional mMDH subunits and detected different patterns of mMDH subunits in two distinct mitochondria types although they were isolated from plants with the same nuclear genotype. These differences are also reflected in isozym patterns, whereas Southern analyses showed no alteration in genome structure. Therefore mitochondria type-specific mMDH modifications are possible.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 195 (1994), S. 793-802 
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Aliphatic homopolyesters and copolyesters based on 1,3-propanediol and containing terephthalic acid as aromatic compounds and sebacic acid as aliphatic compound were synthesized by condensation in bulk. Intrinsic viscosity and weight-average molecular weight were measured. Melting temperatures were studied by differential scanning calorimetry. For all polyesters the biodegradability was tested. Test media were inoculated with either municipal compost eluates or decanted sewage sludge. Criteria measured were visible changes, weight loss, and scanning electron microscopy indicating the visible changes of the surface. Compositions of copolyesters were characterized by 13C NMR spectroscopy. As a major result it is concluded that biodegradability depends substantially on the sequential structure of the polymer.
    Additional Material: 1 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 67 (1995), S. 904-907 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Copolyesters with different stoichiometric compositions, obtained from 1,4-butanediol, adipic acid, and terephthalic acid by molten-state polycondensation, are studied by means of high resolution 13C NMR spectroscopy with respect to copolymer composition and block length distribution. The ratio of aliphatic and aromatic dicarboxylic acids in the polymer, which sensitively influences the biodegradability of the polymers, reflects the initial monomer composition during polycondensation. This indicates that under the conditions applied for polycondensation no loss for example of terephthalic acid due to sublimation occurs. It was found that the aliphatic and aromatic repeating units are randomly distributed within the polymer chain. The experimentally determined average sequence length distribution dependence on stoichiometric copolymer compositions are in accord with ideal polycondensation statistics. In combination with the results of the degradability of aromatic oligomers, predictions about the degradation characteristics of the aliphatic/aromatic copolymers can be made.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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