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  • 1
    Electronic Resource
    Electronic Resource
    Pultruded fiber-reinforced polyurethane-toughened phenolic resin, I. Reactivity and morphology (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 235 (1996), S. 35-45 
    Details
    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: Ein Phenolharz-Polyurethan-Copolymeres wurde aus einem Phenolharz, einem geschützten Polyurethan und p-Toluolsulfonsäure hergestellt. Dieses Copolymere weist trotz großer Härte eine gute Verarbeitbarkeit (einschließlich Topfzeit und Reaktivität) auf. Die Synthese des Copolymeren wurde mit IR-Spektroskopie verfolgt. Es wurde gefunden, daß die Isocyanatgruppe des Polyurethans nach Abspaltung der Schutzgruppe mit der Hydroxygruppe des Phenolharzes reagierte. Glasfaserverstärkte Verbundwerkstoffe offenbarten bei SEM-Untersuchungen eine hervorragende Verbindung zwischen Faser und Matrix. Ein Überlappungspeak im DMA-Diagram wies auf Wechselwirkungen zwischen Phenolharz und Polyurethan hin, die die Härte des Phenolharzes verbessern.
    Notes: A phenolic resin/polyurethane copolymer was synthesized by reaction of a phenolic resin, a blocked-polyurethane and p-toluene sulfonic acid. The copolymer provides a good balance between the processability (including pot life, reactivity) and toughness. The reactions that proceeded during the synthesis of the copolymer was investigated by IR spectroscopy. It was found that blocked polyurethane reacted with the hydroxy group of the phenolic resin. Glass fiber-reinforced composites showed excellent bonding between fiber and matrix as revealed by SEM photographs. An overlap peak was found from the DMA diagram; it indicated that an interaction existed between phenolic resin and polyurethane and that improved the toughness of the phenolic resin.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1996.052350104
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of draw ratio on the structure of aromatic copolyimide fibers of random monomer sequence (1995)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 46 (1995), S. 261-266 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: X-ray methods have been used to investigate the structure of fibers of aromatic copolyimides prepared from 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), o-tolidine (OTOL) and p-phenylene diamine (PPD). We have shown previously that the non-periodic layer lines in the X-ray fiber diagrams of these copolymers are indicative of a random comonomer sequence. In the present paper, we analyze the shifts in the layer line positions that occur with increasing draw ratio. These changes are to be understood primarily in terms of increases in the correlation lengths for the stiff chain conformation. At high draw ratios there is also evidence for the development of a more extended chain conformation, probably due to torsional variation changes in the torsion angles. It is shown that the data are sufficiently sensitive to allow quantitative analysis of these separate effects, and their dependence on comonomer ratio.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1995.010460308
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  • 3
    Electronic Resource
    Electronic Resource
    Studies of macromolecular entanglements.This work was done under the joint auspices of the National Foundation for the Promotion of Natural Sciences and the Doctorial Training Section of the National Education Commission, both of the Chinese Government. I. Melting behavior of swelling polymers with macromolecular entanglements (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 1155-1166 
    Details
    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: In this paper the swelling and melting behavior of several polymers, particularly acrylic fibers, is studied by thermomicroscopy and differential scanning calorimetry in detail. It is confirmed that the protrusion peak on the tail part of the DSC thermogram of swelling polymers is closely associated with the macromolecular entanglements. The proposed swelling DSC method is proved to be very effective for studying polymer entanglements. It is also shown that the melting point, whether of paracrystalline region or of entanglement structural unit, can be well fitted to Flory's melting point depression theory.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420429
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  • 4
    Electronic Resource
    Electronic Resource
    Macromolecular entanglement. III. Textural development of acrylic fibers (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 871-886 
    Details
    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: The texture of a polymer (on fiber) is effectively developed by heat and stress. In this article, the chief material studied is acrylics, usually polyacrylonitile copolymer (PAC fiber) produced by Jingshan Jinglun Fiber Production Plant. In industry, the Jinglun acrylic fiber is heat treated, using saturated steam, at a temperature of 120-130°C to enhance its loop strength, reduce shrinkage, and stabilize crimp. At 140°C, the fiber becomes tacky and its good textile properties seem to deteriorate. At 150-160°C, the texture of the fiber seems to be deeply modified. Tested by differential scanning calorimetry (DSC) with the fiber immersed in a swelling agent (usually termed swelling DSC, abbreviated as SDSC), in addition to the entanglement peaks situated on the latter part of the thermogram of the Jinglun fiber, a new endothermic peak before the crystalline peak (actually, paracrystalline in the case of acrylic fiber) was discovered. The elastic recovery properties of the treated fiber under partially swelling conditions were improved. This seems to indicate that this preparacrystalline peak might also be concerned with entanglements.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070450514
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  • 5
    Electronic Resource
    Electronic Resource
    Internal stress, lattice deformation, and modulus of polymers (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 1779-1791 
    Details
    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: The relationships among internal stress, lattice deformation, and the moduli of polymers, such as poly(ethylene terephthalate) (PET), polypropylene (PP), polyethylene (PE), polyacryonitrile (PAN), and poly(p-phenylene terephthalamide) (PPTA), have been studied systematically. Compared to small molecule crystals, polymer crystals have many more defects and their parameters of the crystal unit cells and the density of the crystalline region are easy to vary to a certain extent. During the processing, external stresses were put on the polymer fibers and polymer molecules were drastically deformed, which induced polymer crystallization and preferred orientation. After processing, there are many macromolecules frozen in the nonequilibrium status, which is the cause of internal stress. Heat treatment could give energy to the macromolecules to release the internal stress and to approach thermodynamic equilibrium. For polymer crystals, the higher the annealing temperature, the shorter the lengths of the unit cell axes, the more integral and regular the crystal lattice, and the smaller the unit cell volume. Crystalline modulus changes not only with different kinds of polymer materials, but also with measurement temperature and processing history. Polymer processing, mainly drawing, causes orientation and internal stress which causes lattice deformation and raises tensile modulus of polymer materials.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420635
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  • 6
    Electronic Resource
    Electronic Resource
    Molecular dynamics simulations of helix folding: The effects of amino acid substitution (1997)
    New York : Wiley-Blackwell
    Biopolymers 42 (1997), S. 633-644 
    Details
    ISSN: 0006-3525
    Keywords: solvent-referenced potential ; multiple minima problem ; single-residue substitution ; helical ratio ; capping effect ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular dynamics simulations were applied to helix folding of alanine-based synthetic peptides. A single alanine residue in the middle of the peptide was substituted with various nonpolar amino acids (leucine, isoleucine, valine, glycine or proline) to study the effect of the substitution. Unlike many other molecular dynamics simulations, nonhelical initial conformations were used in our simulations to study the folding process. An average solvent effect was included in the energy function to simplify the solvent calculation and to overcome the multiple minima problem. During the simulations, the peptides folded into helices in nanoseconds. Compact structures containing two helical segments were also observed. The calculated helical ratios of the peptides showed the same rank order as observed experimentally for the alanine-based peptides. Within a peptide, the helical ratio of each residue was calculated and a minimum was found near the center of the sequence for all peptides. The substitutions had different asymmetric effects on the helical ratios of the residues preceding and following the substitution site, indicating different helix capping preferences of the substituting amino acids. © 1997 John Wiley & Sons, Inc. Biopoly 42: 633-644, 1997
    Additional Material: 4 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Pultruded fiber-reinforced polyurethane-toughened phenolic resin. II. Mechanical properties, thermal properties, and flame resistance (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 62 (1996), S. 227-234 
    Details
    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 novel process has been developed to toughen phenolic resin by polyurethane for fiber-reinforced pultruded composites. The mechanical properties of the composites (tensile strength, flexural strength, and notched Izod impact strength) approach maximum values at 10 wt% of the blocked polyurethane content. The fabricated composites show good mechanical properties and possess low void fraction. Notched Izod impact strength of the composite (with 5 wt% polyurethane content) increases by more than 30% compared to the virgin composite. The thermogravimetric analysis (TGA) showed that the temperature for the 5% weight loss of the phenolic/polyurethane copolymer decreases with the increasing of the polyurethane content; however, the thermal degradation temperature is still higher than 350°C. Differential scanning calorimetric analysis (DSC) showed that the onset point of copolymer is 20°C higher than that of the virgin one. The presence of the blocked polyurethane may hinder the polymerization of phenolic resin. The modified composite shows excellent dimensional stability. The copolymer composite also possesses good fire resistance. © 1996 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Preparation of superconducting edge junctions using polymeric Langmuir-Blodgett films as barrier layers (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 51 (1994), S. 2035-2039 
    Details
    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: Aromatic polyamic acid alkyl ammonium salt exhibits very good transfer behavior under suitable deposition conditions. A superconducting thin film of YBa2Cu3Ox (YBCO) on Langmuir-Blodgett film (LB) has been obtained when the substrate temperature is higher than 500°C. Superconducting edge junctions of (Pb - In)/LB/(Pb - In) and YBCO/LB/YBCO incorporated with polyimide LB films were fabricated. Their current-voltage characteristics are discussed in terms of the temperature stability of polyimde LB films. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070511208
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of surfactants on the particle sizes of red#170 polyurea microcapsules (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 52 (1994), S. 1165-1173 
    Details
    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: Red#170 (pigment) polyurea microcapsules have been successfully prepared at our laboratory. Both core and shell of these microcapsules are demonstrated to be red#170 pigment and polyurea, respectively, by infrared (IR) spectra. The number-average particle sizes of these microcapsules are seen to decrease with increasing concentration and the ethylene oxide chain length of nonylphenylpolyoxyethylene ether (NPn; n = 6, 8, 10, 12, 16) as an emulsifier in the water phase used for making microcapsules. Experimental results indicate that the average particle sizes of red#170 polyurea microcapsules are smaller for the system with NP16 than for the system with NP4 (in the oil phase) and/or NP16 (in the water phase) and that, in the presence of NPn, these particle sizes are seen to be slightly smaller for use of methylcellulose than for use of sodium carboxymethylcellulose as a protective colloid. It is also interesting to note that the released amounts of red#170 pigment from polyurea microcapsules in di-n-butylphthalate solvent is lower for a system with NP16 than for a system with methylcellulose, as a result of good emulsification leading to decrease the interaction between toluene diisocyanate and water molecules. This may further cause more crosslinkage to take place at the urea groups, resulting in a decrease in the porosity of the capsules. © 1994 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070520816
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  • 10
    Electronic Resource
    Electronic Resource
    Studies on macromolecular entanglement. II. Modification of macromolecular entanglements by heat treatment (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 47 (1993), S. 1881-1895 
    Details
    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: The modifications of macromolecular entanglements in polyacrylonitrile copolymer fibers by heat setting in different mediums such as steam, hot air, and inert liquid are reported. The effects of applied tension, frozen internal stress, temperature, time, medium, crystallization, etc., during heat setting on the modification of entanglements are investigated in detail. These experimental results elucidate clearly the mechanism of entanglement and disentanglement and confirm fully the DSC method of swelling polymers for studying entanglement in solid polymer, as was previously published in Part I of this paper. © 1993 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070471018
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