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  • 1
    ISSN: 0360-6384
    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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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 62 (1996), S. 1339-1345 
    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 the present publication, a method to identify and distinguish between different types of low-density polyethylene based on thermal fractionation and FTIR analysis is described. It was shown that during thermal fractionation four to seven endothermic peaks are obtained as opposed to one or two peaks obtained during regular differential scanning calorimetric analysis. The ration between band heights at 1368 and 1376 cm-1 was found to represent the length of the side chain (branch). © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 139 (1986), S. 149-156 
    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: Polymethylmethacrylat (PMMA), Polybutylmethacrylat (PBMA) und Polydecylmethacrylat (PDMA) sind bei Normaldruck mit Toluol im Bereich zwischen Raumtemperatur und Siedepunkt des Lösungsmittels vollkommen mischbar. In Alkanen (C6 bis C10) und Pentanol-1 steigt die Löslichkeit mit der Länge der Seitengruppe des Polymeren: PMMA zeigt stets eine Mischungslücke im oben angegebenen Temperaturbereich, PBMA zeigt obere kritische Lösungstemperaturen (außer bei n-Hexan, das ein Nichtlösungsmittel ist), und PDMA ist mit allen untersuchten Alkanen vollständig mischbar. Alkohole (bis C4) sind Nichtlösungsmittel für PMMA, aber Theta-Lösungsmittel für PBMA und PDMA (außer Ethanol, das ein Nichtlösungsmittel für PDMA darstellt). Die Tieftemperaturentmischung von Ethanol/PBMA wird durch Druck zu tieferen Temperaturen verschoben.
    Notes: Poly(methylmethacrylate) (PMMA), poly(butylmethacrylate) (PBMA), and poly(decylmethacrylate) (PDMA) are completely miscible with toluene at normal pressure from room temperature up to the boiling point of the solvent. In alkanes (C6 to C10) and 1-pentanol the solubility increases with the length of the side chain of the polymer: PMMA always exhibits a solubility gap within the above temperature range, PBMA shows upper critical solution temperatures (except n-hexane, which is a non-solvent), and PDMA mixes completely with all alkanes under consideration. Alcohols (up to C4) are non-solvents for PMMA but theta solvents for PBMA and PDMA (except ethanol which is a non-solvent for the latter). The low temperature demixing of ethanol/PBMA is shifted towards lower temperatures by pressure.
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  • 4
    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: Poly(n-decylmethacrylat), ein statistisches Copolymeres aus Ethylen und Propylen, und ein Zweiblockcopolymeres aus Styrol und hydriertem Butadien wurden repräsentativ für verschiedene Arten von Viskositätsindex-Verbesserern untersucht. Essomarcol 52 und AF 1 von Schindler dienten als öle; Toluol und 1 Phenyldodecan wurden ebenfalls untersucht. Mit Hilfe von Viskositätsmessungen im Temperaturbereich von 37,8 bis 98,9°C und bis zu einer Polymerkonzentration von 1 Gew.-% wurden die Viskositätsindizes und die entsprechenden Grenzviskositätszahlen, Huggins-Koeffizienten sowie Fließ-Aktivierungsenergien, E≠, verschiedener Systeme bestimmt. Die Erörterung der experimentellen Ergebnisse zeigt, daß der Viskositätsindex von öl auf zwei unterschiedliche Arten erhöht werden kann: (i) durch Erhöhung der Viskosität aufgrund der blolßen Anwesenheit von Polymeren ohne Veränderung von E≠ und(ii), weniger häufig, durch Verringerung von E≠ als Folge der thermodynamischen Wechselwirkung. Es werden Gleichungen angegeben, die es erlauben, diese beiden Beitrlge zu berechnen .
    Notes: Poly(n-decyl methacrylate), a statistical copolymer of ethylene and propylene, and a diblock copolymer of styrene and hydrogenated butadiene were studied as representatives of various kinds of viscosity-index (VI) improvers. Essomarcol 52 and AF 1 from Schindler served as base-oils, toluene and 1-phenyl dodecane were also studied. By means of viscosity measurements in the temperature interval from 37.8 to 98.9°C up to a concentration of typically 1 wt.-% polymer, the viscosity indices of the different systems and the corresponding intrinsic viscosities, Huggins coefficients, and activation energies of flow, E≠, were determined. The discussion of the obtained experimental material demonstrates that the VI of a base-oil can be raised in two clearly distinguishable ways: (i) via an increase in the viscosity due to the mere presence of the polymer, without a change in E≠ and (ii), less general, via an additional reduction of E≠ as a consequence of thermodynamic interactions. Formulae are given from which these two contributions can be calculated.
    Additional Material: 10 Ill.
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  • 5
    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: Mit Hilfe der kontinuierlichen Polymerfraktionierung (CPF) wurden 45 g Poly(acrylsäure) (PAA 500) mit einer trimodalen Molmassenverteilung (M̄w = 500 kg/mol, (M̄w/M̄n) -1 = 2,33) in zwei Stufen mit 1,4-Dioxan als Lösungsmittel fraktioniert. Die Gegenstrom-Extraktion wurde in einer Glaskolonne (Länge: 190 cm, Durchmesser: 1,5 cm) durchgeführt, die mit einem Drahtnetzwerk gefüllt war, indem die Lösung 75 cm vom oberen Ende zugeführt wurde. Die Verteilung der Fraktion mit der höchsten Molmasse (M̄w = 760) ist unimodal und vergleichsweise eng ((M̄w/M̄n) -1 = 0,66). Es bestehen Anhaltspunkte, daß die Fraktionierung nicht nur in bezug auf die Molmasse, sondern auch in bezug auf die Taktizität erfolgt.
    Notes: 45 g of poly(acrylic acid) (PAA 500) with a trimodal molar mass distribution (M̄w = 500 kg/mol, (M̄w/M̄n) -1 = 2.33) were fractionated by means of CPF (continuous polymer fractionation) in two steps using 1,4-dioxane as solvent. The counter-current extraction was performed in a glass column (length: 190 cm, diameter: 1.5 cm) filled with a network of wires, introducing the feed 75 cm from its upper end. The distribution of the highest molar mass fraction (M̄w = 760 kg/mol) is unimodal and comparatively narrow ((M̄w/M̄n) -1 = 0.66). Indications exits that fractionation is not only taking place with respect to molar mass but also with respect to tacticity.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 12 (1968), S. 973-974 
    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
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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: Viscosity measurements were carried out as a function of pressure and temperature with solutions of polystyrene in eight (endothermal) θ-solvents at the respective critical composition by means of a Searle-type apparatus. A rolling-ball viscometer was used for the investigation of the pure solvents. In all cases the viscosity coefficient increases in a more or less exponential manner when the pressure is raised. For θ-conditions, the volumes of activation of the solutions exceed that of the pure solvent by typically 10-15%. The exact amount of this extra efffect stemming from the presence of the polymer and its variation with temperature can be qualitatively correlated with the heats of mixing. The ratio of the viscosity of the solution at 1000 and 1 bar, respectively, can be varied for a given solvent power (θ-temperature) by the choice of the solvent from ca. 2 (cyclopentane) to 4 (trans-decalin). Within a given system, the maximum effects that can be realized by a change of the solvent power via the variation of temperature ranges from ca. 3 to 6 (tert-butylacetate).
    Additional Material: 14 Ill.
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  • 8
    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: To adopt a recently developed method for large scale fractionation (CPF = continuous polymer fractionation, a special kind of counter current extraction) to polyisobutylene (PIB), a systematic search for the best mixed solvent was performed. For this purpose, the essential parts of the phase diagrams solvent/nonsolvent/PIB were determined for 21 mixed solvents by cloud-point measurements; with eight systems of special interest, the molecular weight distributions of the polymers contained in the coexisting phases were also studied. On the basis of these experiments and of considerations concerning additional criteria for the performance of the continuous counter current extraction, the mixed solvent toluene/methyl ethyl ketone was chosen. First experiments with a PIB sample of Mw = 420,000 g/mol and a molecular nonuniformity U = (Mw/Mn) - 1 of 2.3 yielded two high molecular weight fractions Mw = 1.1 × 106 and 0.6 × 106 resp., with U = 0.3 on a 100 g scale upon the application of four CPF steps.
    Additional Material: 9 Ill.
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  • 9
    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 quality of polymer fractionation depends on the choice of the mixed solvent as well as on the particular conditions of operating the continuous countercurrent extraction. With a polyisobutylene (PIB) sample of medium molecular weight Mw = 98,400 g/mol and U = (Mw/Mn) - 1 = 1.4 plus the mixed solvents toluene/2-butanone (TOL/MEK) and n-heptane/2-butanone (HEP/MEK) (both giving comparably good fractionation in equilibrium experiments), possible ways to optimize the CPF were tested. The mixed solvent HEP/MEK turns out to be superior to TOL/MEK for kinetic reasons. Due to the larger gap between its density and that of the pure polymer, the coexisting phases can still move through the column, even if the working point of the CPF is chosen close to the consolute point of the ternary system. Under these conditions the mass transfer becomes more rapid, and up to 80% of the (mixed) solvent can be economized as compared with TOL/MEK. Four CPF runs with TOL/MEK (each dividing the polymer material into portions approximately equal in weight, and rejecting the first low molecular fraction) yielded four 200 g samples of Mw ranging from 80,600 to 257,000 with U values of ca. 0.3.
    Additional Material: 13 Ill.
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  • 10
    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: For the first time, a quantitative theoretical analysis (liquid/liquid phase equilibria treated by means of the continuous thermodynamics) of the operating characteristics of continuous polymer fractionation (CPF) was performed. The results of these calculations were compared with data published for CPF of polyethylene. It turned out that the efficiency of the conventional CPF corresponds to approximately two theoretical plates only. For this reason, several improvements, suggested by theoretical considerations, were realized experimentally, for which purpose the system dichloromethane/diethylene glycol/bisphenol-A polycarbonate was chosen. The pulsating sieve-bottom column was replaced by a nonpulsating column filled with glass beads. In this manner, the number of theoretical plates could be raised considerably. A further improvement of the fractionation efficiency results from the reflux of part of the polymer contained in the sol phase. In praxi, this situation was realized by putting a condensor on top of the column and introducing the feed somewhere near its upper third. After predictive calculations and orienting experiments, 125 g of a polycarbonate with Mw = 29 kg/mol and a nonuniformity U = 1.3 were fractionated in four consecutive CPF runs (where the gels were directly used as feed for the next step) into five fractions of approximately equal weight. Except for the lowest-molecular-weight fraction, one obtains nonuniformities on the order of 0.1.
    Additional Material: 11 Ill.
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