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  • Polymer and Materials Science  (313)
  • STRUCTURAL MECHANICS  (79)
  • ASTROPHYSICS
  • 1970-1974  (250)
  • 1960-1964  (142)
  • 1972  (250)
  • 1964  (142)
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  • 1970-1974  (250)
  • 1960-1964  (142)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 6 (1972), S. 59-79 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Advantages of a hollow-fiber hemodialyzer have been well described. The goal of this program was to provide a working model of a noncellulosic hollow fiber artificial kidney with nonthrombogenic blood-contacting surfaces, low blood-priming volume and low pressure drop, a satisfactory rate of urea transport, and high rate of ultrafiltration of water. Also, the reliability and utility of these devices was to be demonstrated through clinical evaluation.
    Additional Material: 9 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 8 (1964), S. 1607-1617 
    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: By means of interfacial polycondensation, ultrathin coatings of polyamides, polyurethanes, polyureas, polyesters, polycarbonates, and various copolymers can be formed on the surface of a substrate. If the substrate contains reactive groups (such as —NH2, —OH, —NCO, —COCl, etc.), graft polymer is formed. The graft polymer is not removed by extensive extraction with good solvents for the polymer. In contrast, if wool is used as a substrate and is acetylated prior to the polymerization (to block the grafting sites), the thin coating of polymer is readily extracted. Digestion of the treated wool with enzymes that react with the wool, but not with the grafted coating, permits a characterization of the grafted polymer; amino acid analysis of the residue from the enzyme digestion provides evidence that the grafting sites on the wool are probably the free amino and hydroxyl groups located in the N-terminal amino acids or internal amino acids containing these groups in their side chain.
    Additional Material: 12 Tab.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 8 (1964), S. 1985-1989 
    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 method for hydroxyl analysis is described in which excess toluene diisocyanate is reacted with a hydroxy compound, preferably in the presence of a catalyst, and the unreacted isocyanate is determined with dibutylamine reagent. The method is particularly applicable to polyethers intended for urethane foam preparation. It is rapid, is accurate, and has the added advantage of including such impurities as would be expected to consume isocyanate during a foam preparation.
    Additional Material: 1 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 8 (1964), S. 2239-2247 
    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: This work is a continuation in these laboratories of the study of the source of undesirable optical properties of molded cellulose acetate. The origin, mechanism of formation, and structure of the colored compounds formed upon heating cellulose acetate in the presence of plasticizer were studied. Extraction of heated mixtures gave evidence indicating the colored compounds are intermediates containing a conjugated carbonyl group. Efforts to fractionate and isolate color-causing fractions were defeated by the well-known solvent inclusion difficulties and upset of the little-understood salt balance in the sample. The effects of additives known to degrade cellulose acetate were determined by heating mixtures of these materials with cellulose acetate dissolved in excess plasticizer. Acidic compounds caused the expected severe degradation and color formation. Air oxidation and free radical initiators had very little effect compared to the acidic materials. Inhibitors of the action of acidic compounds (neutralizers) and of oxidative degradation were studied.
    Additional Material: 7 Tab.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 1377-1386 
    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 molecular bond rupture rate during ozone attack of torsionally loaded rubber was determined from electron paramagnetic resonance (EPR) measurements. The rupture rate was successfully correlated by a Griffith-type energy balance to the strain-energy release rate in the samples. These observations substantiate the results from a similar study on tensile loading previously reported. In both cases there is a one-to-one correspondence between the rate of bond rupture (or crack growth) and the rate of energy release from the strain field and external work. A fracture energy, γn, of approximately 5×10-12 (±20%) ergs per free radical formed during the cracking was experimentally determined.
    Additional Material: 5 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 1313-1330 
    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: An experimental and theoretical study of two-phase flow of molten polymers has been carried out. The theoretical analyses apply the theory of nonlinear viscoelastic fluids to consider stress and velocity profiles and interface shape in stratified flow between parallel plates and in a tube. The second normal stress difference is predicted to influence interface shape. Experimental studies have been made of stratified two-phase flow of a low viscosity but elastic low-density polyethylene and a high-viscosity polystyrene in a capillary rheometer. In the stratified flow experiment, velocity fields and interface shape in the reservoir approaching capillary die and the emerging extrudate were investigated, the former being observed through visual experiments. The emerging extrudates possessed convex polystyrene surfaces at the interface. A strong tendency toward the collection of bubbles near the capillary entry was found. We have made an experimental study of the extrusion of disperse mixtures of polystyrene and different polyolefins. The morphology of the disperse two-phase emerging extrudates has been investigated.
    Additional Material: 6 Ill.
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  • 7
    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: Gel permeation chromatographic (GPC) and thin-layer chromatographic (TLC) studies of polystyrene, polybutadienes (BR), and their copolymers (SBR) have been carried out. GPC primarily separates them on the basis of molecular size, and TLC, on the basis of composition. Methods of obtaining absolute molecular weight distributions for BR and SBR based upon variations of the Strasbourg Universal Calibration procedure are described. In particular, [η]-M relationships in both the GPC solvent (THF) and in a second solvent (toluene) were used; in addition, results of statistical mechanical calculations for \documentclass{article}\pagestyle{empty}\begin{document}$\overline {s^2 }$\end{document} (based on the assumption of negligible steric hindrance and freely rotating bonds) were applied. An experimental comparison of these methods was carried out, and use of the [η]-M relationships for both solvents was found to give satisfactory results. The predictions of the statistical theory were too low. A detailed study of polymer-solvent-gel interaction in the GPC unit was made through investigation of ternary phase equilibrium in the (polystyrene)-THF-(polymer) system. The polymers studied included BR and SBR with varying styrene contents. Experimental techniques for TLC separations of BR, SBR, and polystyrene according to the composition are described.
    Additional Material: 2 Ill.
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  • 8
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The anionic polymerization of styrene was studied in tetrahydropyran as solvent by kinetical and conductivity measurements in order to determine all thermodynamic and kinetical parameters of the formerly proposed three-way-mechanism. These parameters are compared with those in other ethereal solvents. It turns out that the largely differing individual propagation rate constants of the contact-ion pairs, of the solvent-separated ion-pairs, and of the free anions are hardly influenced by the solvent. The unusually great influence of the solvent on the overall polymerization rate is caused by shifting the equilibria between the above mentioned different species.
    Notes: Kinetische und konduktometrische Messungen am System Polystyrl-Natrium in THP werden mit dem Ziel durchgeführt, alle in dem früher vorgeschlagenen dreiteiligen Reaktionsschema vorkommenden thermodynamischen und kinetischen Parameter zu bestimmen und mit den in anderen Lösungsmitteln gefundenen Werten zu vergleichen. Es zeigt sich, daß die Geschwindigkeitskonstanten der Monomeraddition an das Kontaktionenpaar, das solvatgetrennte Ionenpaar und das freie Anion, die sich um Größenordnungen unterscheiden, vom Lösungsmittel nur geringfügig beeinflußt werden. Der ungewöhnlich große Einfluß der Lösungsmittel auf die Polymerisationsgeschwindigkeit geschieht durch Verschiebung der Gleichgewichte zwischen den genannten Formen der Kohlenstoff-Natriumbindung.
    Additional Material: 10 Ill.
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  • 9
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Electron paramagnetic resonance (EPR) spectroscopy was used to compute the surface bond rupture density in polyurethane and to determine the phase experiencing fracture in styrene-butadiene block copolymers when these elastomers are subjected to mechanical degradation by grinding. The polyurethane grinding was done at temperatures above and below the glass transition Tg; 0.155 × 1013 radicals/cm2 of fracture surface area were formed above the Tg and 4.42 × 1013 radicals/cm2 for grinding below the Tg. These values are essentially equal to those found earlier for spherulitic polymers. In all cases the fracture appears able to progress along preferential paths so as to rupture significantly fewer molecular chains than one would expect on the basis of calculations of the number of chains passing through each square centimeter of cross section. Comparison of EPR spectra formed by grinding styrene-butadiene copolymer with those of styrene and butadiene above indicated that at cryogenic temperature, the fracture in the copolymer takes place in the butadiene phase.
    Additional Material: 5 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 1415-1445 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A reaction rate model of fracture in polymer fibers is described. This model assumes that bond rupture is governed by absolute reaction rate theory with a stress-aided activation energy. It is demonstrated that the key in obtaining good agreement between the model and experiment lies in taking proper account of the variation of stress on the tie-chain molecules. The more taut chains rupture first, and the load is redistributed among the remaining unruptured tie chains. The effect of varying the temperature both in the model and in experiments on fracture in fibers is explored. Good agreement between predictions of the model and experiment is possible only with an undeterstanding of the distribution in stress on the tie chains. The distribution in stress on the chains was experimentally determined by monitoring the kinetics of bond rupture with electron paramagnetic resonance (EPR) spectroscopy. Temperature is found to have two effects on macroscopic strength. (1) The thermal energy aids the atomic stress in breaking the atomic bonds; as a consequence the rate of bond rupture of a family of bonds under a given molecular stress is increased. In this respect temperature might be viewed as decreasing the “strength” of a bond. (2) Temperature also serves to “loosen” the molecular structure and in this way modify the distribution in stress on the tie chains. To explain bond rupture and macroscopic fracture behavior quantitatively, account must be taken of both effects.
    Additional Material: 13 Ill.
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