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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial & engineering chemistry 38 (1946), S. 1090-1096 
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    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: Considerable progress has been made in the past 20 years in the synthesis, characterization and fabrication of plastics. Previous SPE Award winners, such as Mark, Natta, and Marvel dealt largely with synthesis; Flory with characterization; Alfrey and Du Bois with fabrication. One of the still unsolved problems lies in the realm of relating mechanical properties, such as impact strenght and creep to molecular structure.The design enginner who wishes to use a plastic part is concerned primarily with how some property such as impact strenght varies with temperature, speed of test, test method, etc. The polymer scientist must know why. Through knowing why, he may be able to design better plastics.This paper attempts to survey some of the world-wide progress made in this area in the past 10 years. The ultimate goal is to understand these mechanical properties in terms of internal molecular motions which occur in solid polymers. Internal motion can be detected by electrical, electromagnetic and dynamic mechanical measurements. When these three methods are applied on a given polymer over a range of temperatures, insights can be gained as to the variation of impact strength and other properties with temperature and frequency for that same polymer. These three fundamental methods, which require very small samples (less than 50 grams), can provide insight into the practical behavior of plastic materials over the wide range of temperatures and frequencies encountered in the real world.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 2009-2009 
    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
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 1245-1275 
    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: Torsional braid analysis (TBA) (∼0.3 Hz) and differential thermal analysis (DTA) data are presented for the temperature for the region 0-200°C for two series of atactic polystyrenes with narrow molecular weight distributions: (a) anionic series, M̄n = 600-2×106, M̄w/M̄n ≃ 1.1; (b) fractionated thermal series, M̄n = 2,000-1.1×105, M̄w/M̄n 〈 1.25. Preliminary results on bimodal blends are also reported. Heating and cooling cycles were employed with TBA; only the heating mode was used with DTA. In addition to a dynamic mechanical loss peak at Tg, a higher temperature loss peak was also found. Designated the Tll or liquid-liquid transition (relaxation), its temperature is 1.1 to 1.2 Tg (°K) for polymers with molecular weight below the critical molecular weight (Mc) for chain entanglements. Above Mc ≃ 35,000, it rises steeply, being ≃200°C for M̄n = 110,000. The common dependence of Tg and Tll on M̄n-1 below Mc suggests a common molecular origin. The two facts, (a) that Tll 〉 Tg and (b) that Tll reflects chain entanglements, further suggest that Tll involves a longer chain segment length and possibly the entire molecule. Comparison of Tll versus log M plots with T versus log M isoviscous state plots based on zero-shear melt viscosity data from the literature implies that Tll measured by the TBA technique corresponds to an isoviscous state of 104-105 poises. The employment of narrow molecular weight polymers is presumably responsible for both the linear variation of the Tll transition with M̄n-1 (which suggests a free volume basis for the relaxation) and the form of the variation of the Tll transition with log M (which suggests an isoviscous basis for the relaxation). The sharpness of the Tll loss peak by TBA decreases with increasing molecular weight and dispersity. The DTA endothermic event corresponding to Tll is clearly related to the occurrence of flow since the fused films which result from heating granules to 200°C and cooling to R.T. do not reveal a Tll on reheating. If a fused film is crushed, a Tll event is observed on heating. For bimodal blends with M̄n 〈 Mc for both components, the Tll transition was averaged; with one component less than and one greater than Mc, the Tll transitions of the components appeared to occur independently at temperatures corresponding to those of the isolated components. In accordance with Ueberreiter and Orthmann, Tg appears to separate a glassy state from a fixed liquid state, whereas Tll separates the fixed liquid from a true liquid state. Possible molecular interpretations for the Tll process are discussed. Systematic bodies of data from the literature which indicate the presence of the Tll process in other polymers are summarized.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
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  • 8
    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: Fourier transform infrared spectroscopy (FT-IR) has been applied to the study of the molecular mechanisms of transitions of atactic polystyrene above Tg. Intensity measurements of vibrational modes as a function of temperature revealed two transitions above Tg, which are designated as Tu and T′u. T′u is independent of molecular weight as opposed to the molecular weight dependent Tu whose behavior is similar to Tg. Infrared measurements are more sensitive to T′u than Tu. Conformationally sensitive bands show that T′u may be related to disruption of local order where there is a negligible barrier to conformational change.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 351-367 
    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: Dynamic mechanical properties have been used as the basis for some important conclusions with regards to the physical properties of rubber-modified high-impact polymers. This paper attempts to show that conclusions of this type should be limited to fairly narrow groupings of polymers. Since the size, shape, and position on the temperature scale of a damping peak are influenced by composition, morphology, and method of polymer preparation, the significance of the damping peak associated with the rubber phase of the polymer has probably been generalized to too great an extent. Two examples of polymer groupings are given to illustrate the need for caution in attaching significance to the dynamic mechanical properties of polymers. Also given are two fairly narrow polymer groupings to show to what extent dynamic mechanical properties can be used for a correlation with impact strength and rubber concentration.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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