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  • 1990-1994  (12)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 217 (1994), S. 159-190 
    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: Mit einer Reihe unterschiedlicher Methoden wurde versucht, die Zähigkeit tri- und tetrafunktioneller Epoxid- sowie ungesättigter Polyesterharze zu erhöhen. Die Epoxidharze wurden durch harte, thermisch stabile Konstruktionskunststoffe, ein Bisphenol-A Polycarbonat bzw. ein thermoplastisches Polyetherimid (Ultem 1000), modifiziert. Bei den ungesättigten Polyesterharzen wurde ein anderes Verfahren angewendet: Zwei handelsübliche flüssige Kautschuke wurden chemisch modifiziert, um ihre Reaktivität gegenüber den funktionellen Gruppen der Matrix zu steigern: Ein hydroxyterminiertes Polybutadien und ein aminoterminiertes Butadien-Acrylnitril-Copolymeres wurden zu Polymeren mit Isocyanat- bzw. Maleimidendgruppen umgesetzt. Ein weiteres hier beschriebenes System zielt darauf ab, die rasch abnehmende Steifheit der Polyestermatrix bei Temperaturen oberhalb Raumtemperatur zu verringern. Dazu wurde ein hitzehärtbares Bismaleimidharz als zweite co-reaktive Komponente in den Polyester eingebracht.
    Notes: A number of different approaches were used to enhance the toughness of tri- and tetrafunctional epoxies and of unsaturated polyester resins. In the case of epoxies, tough, thermally stable, engineering thermoplastics, namely a bisphenol-A polycarbonate and a thermoplastic poly(ether imide) (Ultem 1000) were employed as modifiers. For unsaturated polyesters a different approach was adopted: two commercial liquid rubbers were chemically modified to enhance their reactivity towards the matrix functionalities. In particular, a hydroxy-terminated polybutadiene and an aminoterminated butadiene-acrylonitrile copolymer were transformed into isocyanate-terminated and maleimide-terminated rubbers, respectively. A further system which is described in the present contribution is aimed at mitigating another deficiency of the polyester matrix, namely its rapidly decreasing rigidity at temperatures above room temperature. In this case, a thermosetting bismaleimide was incorporated into the resin as a co-reactive second component.
    Additional Material: 28 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 210 (1993), S. 129-141 
    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: Blends aus Poly-ε-caprolacton (PCL) und Poly(β-hydroxybyurat-co-β-hydroxyvalerat) (PHBV) mit 4 mol-% Hydroxyvalerat-Anteil wurden durch Mischen der Polymeren sowohl ohne Initaiator als auch in Gegenwart von Dicumylperoxid (DCPO) bei 160°C oder Dibenzoylperoxid (DBPO) bei 100°C hergestellt. Es wurden PCL/PHBV-Blends mit dez Zusammensetzungen 30/70 und 70/30 Gew.-% hergestellt. Zum vergleich wurden diereinen Polymeren ebenfallsmit DCPO bei 160°C umgesetzt. Die Produkte wurden thermisch (DSC) und Mechanisch (Zugversuche) sowie mittels Rasterrelektronenmikroskipie (SEM) untersucht. SIgnifikateUnterschiedein den chemisch-physialischen Eigenschaften der Beldns Konnten auf den Einfluß sowohl des Initiators als auch der Temperatur zurückegeführt werden.
    Notes: Blends of poly-ε-caprolactone (PCL) and poly(β-hydroxybutyrate-co-β-hydroxy-valerate) (PHBV) containing 4 mol-% of hydroxyvalerate were prepared by mixing the two polymers in the presence of either dicumylperoxide (DCPO) at 160°C or dibenzoylperoxide (DBPO) at 100°C. Similarly, blends were obtained by mixing the two polymers without any peroxide added. The blends were prepared in to complementary compositions, namely 70 wt.-% PCL/30 wt.-% PH BV and 30 wt.-% PCL/70 wt.-% PHBV, respectively. Also pure polymers were reacted with DCPO at 160°C in the same way as the blends.Thermal (DSC), mechanical (tensile tests) and SEM analyses were performed on the blends and on the pure polymers.Significant differences were found in the chemical-physical characteristics of blends with and with out peroxides as well as in blends prepared at low and high temperatures.
    Additional Material: 5 Ill.
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  • 3
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 6 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 13 (1992), S. 231-235 
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 12 (1991), S. 563-570 
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 6 Ill.
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  • 6
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: By using optical microscopy, small-angle X-ray scattering and differential scanning calorimetry, the melting behaviour and the structural parameters of poly(ethylene oxide)/poly(methyl methacrylate) (PEO/PMMA) blends are determined. The equation that relates the observed melting temperature, Tm′, to the lamellar thickness is used for the determination of the equilibrium melting temperature, Tm. In the case of blends a small depression in the equilibrium melting point is observed. The depression is dependent on composition. the interaction parameter obtained from the melting point degression, by using the Nishi and Wang equation, was found to be = -0,29. The superstructural parameters are dependent on blend composition, under cooling and sample preparation.
    Additional Material: 7 Ill.
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  • 7
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A preliminary investigation on the influence of the coagulation process on the solid-phase structure of poly(1,3,4-oxadiazole-2,5-diyl-1,4-phenylene) (1) is reported. Interesting correlations between the method of coagulation of the polymer from sulfuric acid solution and the structure which develops, as observed by thermal analysis, X-ray diffraction, infrared spectroscopy, and optical microscopy are found. A new method for the preparation of highly crystalline spherulites of 1 is described. This method allows to grow a relatively large number of “single spherulites”, because coagulation and crystallization induced by a non-solvent may be stopped before impingements occur.
    Additional Material: 8 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 669-679 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Blends of poly(1,3,4-oxadiazole-2,5-diyl-1,4-phenylene) (PODZ) and polyamide 6 (PA6) were obtained by a coagulation process from sulfuric acid solution. The resulting blends were studied by means of X-ray diffraction and calorimetry using a DSC and a thermogravimetric apparatus. The PA6 crystallinity was found to be strongly influenced by the presence of PODZ and is dependent on the blend compositions. Below 30 wt.-% of PA6 crystallinity disappeared completely. A preliminary investigation of morphology and mechanical properties was also carried out.
    Additional Material: 9 Ill.
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  • 9
    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.
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  • 10
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 383-391 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 effect of short-length carbon and Kevlar fibers on the crystallization of isotactic polypropylene (iPP) in composites prepared by compression molding has been investigated. The tendency of carbon and Kevlar fibers to nucleate the iPP during isothermal and nonisothermal crystallization has been evaluated by differential scanning calorimetry. The influence of different thermal histories used to prepare the unreinforced and reinforced samples on the crystallization parameters of iPP was examined. In addition, the tensile behavior was related to the resulting morphologies of the samples. It was observed that the crystallinity content, obtained by using different thermal treatments (slowly cooling or quenching), gives rise to different morphologies by influencing the mechanical behavior of materials as well. Moreover, the composites obtained by slow cooling seem to present a better fibber/matrix adhesion then that found in quenched samples. Possible underlying microstructures, which can explain the properties and the morphological characteristics, are also discussed.
    Additional Material: 21 Ill.
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