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  • Polymer and Materials Science  (120)
  • Chemical Engineering  (45)
  • AERODYNAMICS
  • GENERAL
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  • 1965-1969  (252)
  • 1955-1959
  • 1966  (252)
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Keywords
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  • 1965-1969  (252)
  • 1955-1959
Year
  • 1
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Crystallization kinetics of crystalline fractions of propylene oxide polymers made with different catalysts have been studied by isothermal dilatometric and microscopical measurements. Isothermal microscopical measurements indicate that spherulite growth in these polymers proceeds from predetermined nuclei. The half time for spherulitic appearance is less than, but of the same order as, the half time for complete crystallization. Only by taking this factor into account can the dilatometric data be represented by the Avrami equation. The deviation of the crystallization isotherm from that predicted from the microscopical data using the Avrami theory is attributed to a secondary crystallization process taking place within the spherulite. Crystallization continues long after spherulites completely occupy the available volume in the polymer. By assuming that the secondary crystallization proceeds as a first-order process in the uncrystallized, but crystallizable, portions of the melt, it is shown that the crystallization isotherms can be completely described in terms of four parameters. These are: (1) the time constant for the primary crystallization process; (2) the time constant for nucleation; (3) the time constant for the secondary crystallization process, and (4) the extent of secondary crystallization. The important conclusions of these studies are: the rates of nucleation and of spherulitic growth are far more dependent on temperature than on stereoregularity; the ratio of the rate of the secondary crystallization process to that of the primary crystallization process is almost independent of temperature, but increases with increasing stereoregularity of the polymer.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 10 (1966), S. 75-80 
    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: Relaxation times of polyethylene melts have been measured by Aloisio, Matsuoka, and Maxwell. One implication regarding their observations is that the elastic properties of polymer melts must be time-dependent. In particular, the steady-flow shear modulus depends on the strain rate. Some interpretations of data in the literature have been based on concepts in rubber elasticity where the steady-flow modulus is an equilibrium value, independent of strain rate. We have used Pao's theory for viscoelastic flow together with measurements of relaxation times to discuss the strain rate dependence of the steady-flow shear modulus of melts. The existence of a strain rate-dependent shear modulus leads naturally to a nonlinear relation between shear stress and recoverable shear strain. The conclusions regarding the molecular weight dependence of the modulus also differ from interpretations based on rubber elasticity.
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 12 (1966), S. 606-608 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 12 (1966), S. 1026-1026 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 12 (1966), S. 819-822 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 6 (1966), S. 65-70 
    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: Moisture present in epoxy anhyride composites may hydrolyze the anhydride and cause major changes in the mechanical and chemical properties of the final composite. Heat distortion data and infrared spectroscopy are used to analyze the changes caused by the presence of the moisture. As the concentraton of water is increased, there is a decrease in the heat distortion or gass transition temperature. The decrease is due to a change in the crosslinking network and is caused by the reduction of the functonality of the epoxy group for acid as compared to the anhydride. Where rigid specifications must be met it is essential that the moisture level in the fillers, resins, etc. be kept constant.
    Additional Material: 5 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 10 (1966), S. 1725-1735 
    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 new high-temperature elastomer, SiB-2, has been investigated by stress relaxation, modulus-temperature, and volume--temperature techniques. SiB-2 was found to be more stable than a related elastomer, radiation-cured silicone rubber, having about twice as long as a chemical relaxation time at 250°C. Possible mechanisms to account for this increased stability are discussed. At low temperatures, Tg for SiB-2 was estimated at -34°C., which compares well with Ti = -30°C. for this polymer. By comparison, SiB-3 has Ti = -60°C., while phenyl-modified SiB-4 was found to have Ti = -25°C. Tm for SiB-2 was estimated to be + 56°C.
    Additional Material: 9 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Letters 4 (1966), S. 809-814 
    ISSN: 0449-2986
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Letters 4 (1966), S. 447-452 
    ISSN: 0449-2986
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Copolymerization of propylene and 1-butene with highly stereospecific three-component coordination catalysts produced multiblock crystalline copolymers having stereo-regular sequences of both propylene and 1-butene. Copolymers containing from 3 to about 80% 1-butene had two DTA melting points which were attributable to polypropylene and poly-1-butene crystallinity. Those containing from 18 to about 70% 1-butene had x-ray diffraction patterns showing peaks characteristic of polypropylene and form I poly-1-butene, but form II poly-1-butene crystallinity was never observed. The multiblock copolymer structure observed is also supported by the fact that the product of the reactivity ratios is greater than unity. The composition distributions of low-conversion and continuously prepared copolymers were similar and relatively broad. For example, copolymers containing an average of 12% 1-butene had species containing from 5-30% 1-butene. High-conversion copolymers had an even broader composition distribution due to the gradual increase of the 1-butene concentration in the comonomer mixture as the copolymerization proceeded. The absence of homopolymers was demonstrated by fractionation. The ability to detect homopolymers was proved by the fact that a mixture of stereoregular polypropylene and poly-1-butene were readily separated. Increasing the amount of 1-butene tended to decrease those properties dependent upon crystallinity such as hardness, tensile strength, stiffness, density, and melting point, but tended to improve significantly the impact strength, low temperature properties, and clarity of molded objects. These duocrystalline copolymers retained a much higher level of properties than that observed for random copolymers prepared with less stereospecific coordination catalysts.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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