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  • Chemical Engineering  (5)
  • 2020-2024
  • 1975-1979  (5)
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  • 1
    Electronic Resource
    Electronic Resource
    Polyphosphazenes: Synthesis - properties - applications (1975)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 321-338 
    Details
    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: Various aspects of polyphosphazene chemistry are reviewed. Stable poly (organophosphazenes) can be prepared from an inorganic precursor, poly(dichlorophosphazene), by careful control of polymerization and substitution reaction conditions. The bulk structure and properties of polyphosphazenes are discussed, and attention is given to those polymers which have promise as useful engineering materials. The successful preparation of stable poly(organophosphazenes) appears to have resulted in a new class of polymers for both specialty and large scale commercial development.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760150502
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  • 2
    Electronic Resource
    Electronic Resource
    Transition behavior and phase segregation in TDI polyurethanesPresented part at the American Chemical Society Meeting. Philadelphia (1975). (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 73-80 
    Details
    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: Prior studies of two series of segmented polyurethanes based on 2, 4 toluene cliisocyanate (2, 4 TDI) or 2, 8 TDI, butanediol, and a 1000 molecular weight polytetramethyleneoxide (PTMO-1000) soft segment revealed a rapid increase in soft segment glass transition temperature (Tg) with increasing urethane content in the 2, 4 TDI series. The change in Tg couldbe correlated with estimates of hard segment-soft segment phase mixing obtained by infrared analysis of the urethane NH and carbonyl bands. In the present paper, the infrared data have been reevaluated using improved procedures for resolving the carbonyl band into H-bonded and nonbonded components, and the relation between the estimated extent of phase mixing and Tg has been reexamined. The transition behavior in an extensive series of related polymers has also been determined, including 2, 4 TDI arid 2, 6 TDI samples with PTMO2000 as well as polybutyleneadipate (PBA-1000 and PBA-2000) soft segments. The results indicate the effectiveness, of increased soft segment molecular weight in promoting phase segregation, imply that much greater phase mixing occurs in polyester than polyether samples, suggest that anchoring the ends of the soft segments has only a small effect on Tg, and provide some evidence that H-bonding not only increases Tg but can also impede soft segment crystallization.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760170203
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  • 3
    Electronic Resource
    Electronic Resource
    DSC and TBA studies of the curing behavior of two dicy-containing epoxy resins (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 304-312 
    Details
    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 curing behavior of two commercial dicy-containing resins (I & II), both with recommended cures of 127°C/2 h, has been studied by differential scanning calorimetry (DSC), torsional braid analysis (TBA) and Fourier Transform infrared spectroscopy. Compositional analysis reveals that the two resins differ primarily in the amine/epoxy ratio and the nature of the main epoxy components. Factors contributing to the complex curing behavior observed with II are identified. Isothermal kinetic runs by DSC and TBA lead to estimates for the conversion at the gel point, and to results which suggest that the reactions of epoxy with amine and hydroxyl occur with similar activation energies and similar heats of reaction.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190413
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  • 4
    Electronic Resource
    Electronic Resource
    A dynamic mechanical study of the curing reaction of two epoxy resins (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 313-318 
    Details
    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 curing behavior of two commercially formulated epoxy resins composed of the tetrafunctional amine dicyandiamide and with differing epoxy components, 4,4′-bisglycidylphenyl-2,2′-propane and the tetraglycidyl ether of methylene dianiline, is characterized by dynamic spring analysis. This supported viscoelastic technique is well suited to the determination of the onset of gelation under isothermal conditions but the method is not useful for monitoring later stages of reaction when the resins become more rigid. The activation energy for the curing of the two resins is about 87 kJ/mole (20.7 kcal/mole). Rate constants for the first order curing reaction are given. Additional studies of films cured below the ultimate Tg show that two relaxations can be observed upon heating. The first relaxation occurs near the original isothermal cure temperature with a low activation energy, about 250 kJ/mole, whereas the second relaxation occurs near the ultimate Tg, under the conditions used here, with an activation energy of 500-650 kJ/mole. It is believed that these activation energies provide a unique method of characterizing the molecular mobility of epoxy resins at various states of cure.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190414
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  • 5
    Electronic Resource
    Electronic Resource
    Thermal transition behavior of polybutadiene containing polyurethanes (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 1122-1128 
    Details
    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 thermal transition behavior of a series of hydroxy terminated polybutadiene (HTPBD) containing segmented polyurethanes has been studied by differential scanning calorimetry (DSC) and thermal mechanical analysis (TMA). Four transition regions are observed; the soft segment Tg, at -74°C, two hard segment transitions T1, at 40°C and T2 at 103°C and a softening region by TMA at 180°C, presumed to arise from the dissociation of allophonate bonding, The low Tg, only 7°C higher than the Tg of free HTPBD, indicates nearly complete phase segregation despite the amorphous nature of the hard segment structure. The dependence of T1, on hard segment length and thermal cycling suggests that it represents domains consisting primarily of shorter hard segments units. Factors contributing to the rather low mechanical properties of HTPBD polyurethanes are also discussed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760191510
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