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  • 1
    ISSN: 1572-8900
    Keywords: PHBV ; polyacrylate ; reactive blending ; biodegradation ; properties
    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 The biodegradability of a multicomponent system based on biotechnological occurring polyester (poly(β-hydroxybutyrate-co-β-hydroxyvalerate) (PHBV)) with inclusion of acrylate elastomer (polybutylacrylate) (PBA) was investigated. A bacterium which produced extracellular enzymes that degrades PHBV even when blended with PBA was isolated and tentatively designated asAureobacterium saperdae. It was observed, by morphological investigation, that, while the bacterial degradation was permitted for PBA content of 20% by weight, it was inhibited for PBA content of 30%, owing to the occurrence of a rubbery layer that prevents to the bacteria an easy accessibility in the PHBV-rich regions. In fact, owing the bacterial growth, only PHBV was metabolized, whereas no degradation of PBA was detected for blend samples. It was confirmed that the degradation proceeded via surface erosion of PHBV also in the blends. Finally, mechanical tests on PHBV/PBA specimens as a function of degradation extent have shown different behavior of the blends at different the PBA content. Thermal analysis of blends and PHBV has been reported, too
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 1589-1596 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Isothermally crystallized blends of isotactic poly(1-butene) (PB-1) with hydrogenated oligo-(cyclopentadiene) (HOCP) were annealed for different periods of time and at different temperatures and then analyzed by differential scanning calorimetry. The HOCP, a glassy oligomer with a relatively high Tg value, results with PB-1 in a one-phase system in the melt. The kinetics of crystal transformation of poly(1-butene) from form II to form I are subject to the influence of the non-crystallizable component on the amorphous phase of PB-1. The phase transformation process was also analyzed by means of the Avrami equation. During the conversion process secondary crystallization of PB-1 was observed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The biodegradability of solution-cast films of poly(D(-)-3-hydroxybutyrate) (PHB) blended with the melt-compatible component atactic poly(epichlorohydrin) (aPECH) was investigated. A bacterium which produced extracellular enzymes that degraded PHB even when blended with aPECH was isolated, and tentatively designated as Aureobacterium saperdae. The growth rate of A. saperdae decreased with increasing aPECH content in the blend, up to films containing 60 wt.-% aPECH, at which composition growth was completely inhibited. The decrease in the bacterial growth rate could be due to the dilution of PHB molecules on the blend film surface caused by the presence of aPECH molecules. At the stationary phase of bacterial growth the percentage of weight loss of blend films decreased with increasing aPECH fraction, which was probably due to the lower accessibility of PHB when blended with aPECH. During the bacterial growth only PHB was metabolized, whereas neither degradation nor abiotic release of aPECH was detected for blend films.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 199 (1998), S. 695-703 
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Blends of poly(3-hydroxybutyrate) (PHB) and ethyl cellulose (EtC) were prepared by compression molding of solution cast films. The two components were not miscible but the blends showed ‘mechanical compatibility’. Two PHB/EtC blends (80/20 and 50/50 (w/w in all cases)) were selected for biodegradation experiments in activated sludge and in enzymatic solution of PHB-depolymerase from Pseudomonas lemoignei and from Aureobacterium saperdae. Blend morphology was quite different: blend 80/20 was composed of a matrix of impinging PHB spherulites with dispersed EtC inclusions, whereas blend 50/50 was constituted of two continuous phases with interpenetrated domains. Both blends biodegraded in activated sludge, but only blend 80/20 was attacked by PHB-depolymerases from P. lemoignei and A. saperdae. From weight loss, thickness and composition measurements after different exposure times and from scanning electron microscopy of the biodegraded blend surface it was concluded that in blend 80/20 biodegradation of the PHB matrix caused concomitant release in the medium of the embedded EtC particles. The results on PHB/EtC (50/50) after sludge exposure demonstrated that in this blend the PHB phase - thanks to its interconnected domains - was continuously accessible to microbial attack, leaving a highly cavitated ethyl cellulose structure after PHB consumption. The lack of biodegradation of blend 50/50 in enzymatic solution was tentatively attributed to changes of surface hydrophobicity induced by large amounts of EtC, which disfavored enzyme binding.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 5
    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: Three poly(ethylene terephthalate) films were prepared having the same crystallinity but different morphology. They were colored with azo dyes XC6H4N = NC6H4N(C2H5)2 (where X is H, OCH3, CN, and COOC2H5). The kinetics of the thermal cis-trans isomerization of these dyes has been studied below the glass transition temperature in the range 25-56°C. The isomerization process was found to be the result of a multiplicity of first-order reactions. The kinetic parameters have been correlated with the order degree at molecular level of the polymer. Lightfastness of the dyes in the polymer matrices has been also investigated: it appeared to be in relation with the supermolecular structure of the film.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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