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  • Wiley-Blackwell  (13)
  • Springer  (9)
  • 1990-1994  (22)
  • 1
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A family of aromatic and semi-aromatic polythioetheramides was prepared from well-defined diamine-terminated oligo(thio-1,4-phenylene)s (PPS-DA) containing n=1,2,3,4,5,6 thio-1,4-phenylene units. Polycondensation reactions with adipic, sebacic, terephthalic and isophthalic acid chlorides were carried out in N-methyl-2-pyrrolidone solution at room temperature to yield amorphous and semi-crystalline polythioetheramides. The influence of the oligo(thio-1,4-phenylene) segment lengths on phase transitions and thermal degradation of the polythioetheramides was investigated. As a function of the PPS segment lengths, glass transition temperatures vary between 120°C and 300°C, and melting temperatures between 290°C and 500°C. The thermal stabilities determined by thermogravimetric analysis under nitrogen increase with increasing PPS segment lengths. In the case of the higher molecular weight PPS segments, the resulting semi-aromatic polyamides exhibit two crystalline phase transitions.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Polymer bulletin 32 (1994), S. 361-365 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Organosolv lignin was used as organic filler for polypropylene (PP) and poly(ethene-co-vinylacetate) (EVA) containing 13wt-% vinylacetate. As a function of the lignin content, which was varied between 0 and 30wt-%, mechanical properties such as Young's modulus, yield stress, fracture stress, and elongation at break of the thermoplastic lignin-based compounds were measured. Both lignin-filled thermoplastics exhibit pronounced matrix reinforcement with increasing lignin content. Due to better interfacial adhesion between lignin and EVA, 30wt-% lignin addition to EVA doubles Young's modulus without sacrificing high elongation at break.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A broad range of crosslinked polyesters were prepared by curing epoxidized soybean oil with various dicarboxylic acid anhydrides in the presence of cure catalysts such as tertiary amines, imidazoles, or aluminum acetylacetonate. The mechanical and thermal properties of the casting resins were dependent upon the type of anhydride. While the anhydrides of hexahydrophthalic acid, succinic acid, and norbornene dicarboxylic acid yielded highly flexible rubbery materials with glass transition temperatures below room temperature, the more rigid anhydrides of maleic and phthalic acid gave amorphous stiff polyesters with higher glass transition temperatures varying between 43 and 73°C. When the cure reaction was carried out in polypropylene melts, multiphase polymers were formed containing polyester phases dispersed in the continuous polyolefin matrix.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Polymer bulletin 33 (1994), S. 521-528 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Poly(styrene)-block-poly(ethyleneoxide), abbreviated as (PS-b-PEO) were used as emulsifiers in emulsion polymerization of styrene and methyl methacrylate. The block copolymers had a poly(styrene) block with Mn=1000 g/mol and a poly(ethyleneoxide) block with Mn=1000, 3000 or 5000 g/mol, respectively. Stable dispersions were obtained when the PEO block molecular weight was higher than 1000 g/mol. Also the amphiphilic properties of the copolymers depended on the PEO chain length. Block copolymer micelles with hydrodynamic radii between 11 and 17nm were observed. Emulsion polymerization was performed at different block copolymer concentration at 60 and 80°C. Particle size varied between 50 and 300nm and decreased with increasing copolymer concentration. The particle size was larger at higher temperature, but the size distribution was narrower. Polymerization of methyl methacrylate gave smaller particles when compared to styrene. The dispersions were very stable towards high electrolyte concentration, but flocculation occurred at elevated temperatures. Both observations indicate that the dispersions are sterically stabilized.
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  • 5
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Living polystyrene microparticles with average particle diameters varying between 0.5 and 3.8 μm were obtained via sec-butyl lithium-initated anionic polymerization of styrene in n-hexane diluent when polystyrene-block-poly(4-trimethyl-silylstyrene) was added as dispersing agent. The influence of block copolymer molecular architecture and concentration as well as polymerization temperature, monomer concentration and THF addition on polystyrene particle size, molecular weight and molecular weight distribution were investigated. In comparison to anionic styrene polymerization in cyclohexane solution, the anionic styrene dispersion polymerization in n-hexane was markedly slower.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A series of soluble 6F polyimides were prepared from monodisperse diamineterminated oligo(phenylene thioether)s varying the number of phenylene thioether units between one and six. In a formic acid/hydrogen peroxide slurry the 6F poly(arylene thioether imide)s were converted into the corresponding poly(arylene sulfone imide)s containing controlled oligo(phenylene sulfone) segments. The oxidation process and the influence of oligo(phenylene thioether) and oligo(phenylene sulfone) segments on polymer phase transitions and thermal degradation were investigated.
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  • 7
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Polymerization of N-(p-aminobenzoyl)-caprolactam (PAC) in melts of polyols such as dihydroxy-terminated oligo(oxytetramethylene) with Mn=2000 g/mol at 200°C afforded stable dispersions of poly(p-phenylenebenzamide) whiskers in polyol. In spite of the low molecular weight of the polyaramide, which was isolated by solvent extraction, the microparticles are efficient reinforcing agents of polyurethanes because of the excellent interfacial adhesion resulting from covalent attachment of the polyols onto the microparticle surfaces. The role of the competing formation of p-aminobenzoate-terminated polyols via esterification of PAC was investigated. Morphological and mechanical properties of polyurethane microcomposites, prepared from poly(p-phenylenebenzamide)/poly(oxytetramethylene)diol dispersions and 4,4′-diisocyanatodiphenylmethane, were determined as a function of the microparticle content. When compared to conventional polyurethanes, containing equivalent amounts of spherical organic and inorganic fillers, the microcomposites give higher Young's modulus, tensile strength without sacrificing high elongation at break.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Polymer bulletin 32 (1994), S. 403-410 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Two novel families of dimethacrylate-based thermoset resins containing oligo(tetrafluoroethene) segments with n=1, 2, 3 tetrafluoroethene units were prepared from dimethyl tetrafluorosuccinate, dimethyl octafluoroadipate and dimethyl dodecafluorosuberate. Methacrylate functionalities were determined using1H-NMR spectroscopy. Photocrosslinking by UV irradiation in the presence of photoinitiators affords amorphous networks. The influence of the oligo(tetrafluoroethene) segment length on glass transition temperatures, swelling, volume shrinkage and thermal degradation was investigated.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Polymer bulletin 32 (1994), S. 697-704 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Reactive blending of 70 vol.-% polypropylene (PP) and 30 vol.-% polyamide-6 (PA-6) was performed in the presence of various amounts of succinic-anhydride-functional elastomers which are immiscible with both blend components. Characteristic morphological feature of the resulting multiphase polymer blends was a continuous polypropylene matrix containing dispersed core/shell microparticles with rigid polyamide-6 core and soft elastomer shell. Accumulation of the elastomer component at the polypropylene/polyamide-6 interface and reaction of the succinic anhydride of the elastomer with the amine-endgroups of PA-6 enhanced PA-6 dispersion and proved to be the key to unusual property synergisms. In contrast to the conventional soft maleicanhydride-grafted EPM elastomer (EPM-g-MAH), the stiffer maleic-anhydride-grafted poly[styrene-b-(ethene-co-butene-1)-b-styrene] (SEBS-g-MAH) was much more efficient as blend compatibilizer and gave PP/PA-6 blends with greatly improved strength and toughness without sacrificing stiffness.
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  • 10
    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: Maßgeschneiderte segmentierte Polymere spielen eine Schlüsselrolle bei der Entwicklung von neuen polymeren Materialien. In Abhängigkeit von den molekularen Architekturen der segmentierten Polymeren kann die Ausbildung von Polymermorphologien und von Eigenschaftssynergien gesteuertwerden. An ausgewählten Beispielen werden grundlegende Konzepte und neuere Entwicklungen vorgestellt. Segmentierte Silikon-Flüssigkautschuke, wo unverträgliche Silikonsegmente von zwei mischbaren Oligo(caprolacton)-Segmenten flankiert werden, sind wirkungsvolle Zähmodifikatoren für Epoxidharze. In nanophasenseparierten IPNs auf Basis dieser Silikon-modifizierter Epoxidharze kann die Schlagzähigkeit ohne Verlust der Dimensionsstabilität erhöht werden. Kompatibilisierte Blends aus segmentierten phenolischen Polyurethan- und epoxidfunktionellen Nitril-Flüssigkautschuken bilden diskrete Blend-Mikrophasen, die in Epoxidprepregs dispergiert sind und strukturelles Verkleben von Aluminium in Faser-Metall Laminaten ermöglichen. Reaktive Blendtechnologien werden entwickelt, um während der Polymerverarbeitung, z.B. von Polypropylen/Polyamid 6 Blends, in-situ Phasenvermittler herzustellen. Durch Einbau von definierten Oligo(tetrafluoroethene) Segmenten in Kodensationspolymere werden neben thermischen und mechanischen Eigenschaften auch Oberflächenspannungen und Gasdurchlässigkeiten variiert.
    Notes: Tailor-made segmented polymers play a key role in the development of novel polymeric materials exhibiting unsual bulk and surface properties. As a function of molecular architectures of segmented polymers, it is possible to control polymer morphologies and to achieve property synergisms. Selected examples are presented to illustrate basic concepts and recent developments. Segmented reactive liquid rubbers, containing an immiscible silicone segment flanked by two miscible oligo(caprolactone) segments, are efficient epoxy toughening agents. In such nano-phase-separated silicone-modified IPNs impact strength is improved without sacrificing dimensional stability. Compatibilized blends of segmented phenolic polyurethane and nitrile liquid rubbers produce rubber blend microphases dispersed in epoxy prepregs which are used to bond aluminum sheets in structural laminates. Reactive blending technologies are developed to produce segmented polymers as blend compatibilizers during melt processing, e.g., of polypropylene/polyamide 6 blends. Incorporation of oligo(tetrafluoroethene) segments into various condensation polymers modifies thermal and mechanical properties as well as surface tension and gas permeabilities.
    Additional Material: 13 Ill.
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