Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Rapid assessment of weathering stability from exposure of polymer films. II. The effectiveness of different regions of the solar spectrum in degrading an ABS terpolymer (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 1173-1179 
    Details
    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 simple and rapid method has been developed to determine the relative effectiveness of the different regions of the solar spectrum in weathering a polymer. The method is based on measuring the rate of degradation of the polymer in film form, exposed outdoors under a range of materials which transmit different amounts of solar UV. The stability of an unpigmented ABS terpolymer has been examined using this method. It has been shown that the relatively small amount of solar radiation in the range of 295-340 nm accounts for 41% of the total degradation process. Longer wavelengths are shown to be progressively less effective; wavelengths greater than 450 nm (which account for nearly 90% of the total energy of the solar spectrum) contribute less than 5% to the degradation process.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1974.070180415
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    A world-wide program for the continuous monitoring of solar UV radiation using poly(phenylene oxide) film, and a consideration of results (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 1165-1174 
    Details
    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 use of poly(phenylene oxide) film to monitor UV radiation is demonstrated, and the results from the continuous monitoring of solar UV radiation at 24 sites throughout the world are presented. The global and diffuse measurements from a temperate and from a tropical site are analyzed in detail, and the effects of season and weather conditions on the UV contribution to solar radiation and the relative importance of the diffuse and direct components of solar UV are discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1976.070200503
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Suppression of pyritic sulphur during flotation tests using the bacterium Thiobacillus ferrooxidans (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 30 (1987), S. 1-8 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Environmental concern about sulphur dioxide emissions has led to the examination of the possibility of removing pyritic sulphur from coal prior to combustion during froth flotation, a routine method for coal cleaning at the pit-head. The bacterium Thiobacillus ferrooxidans was effective in leaching 80% and 63% -53 μm pyrite at 2% and 6% pulp density in shake flasks in 240 and 340 h, respectively.The natural floatability of pyrite was significantly reduced in the Hallimond tube following 2.5 min of conditioning in membrane-filtered bacterial liquor prior to flotation. The suppression effect was greatly enhanced in the presence of Thiobacillus ferrooxidans. A bacterial suspension in pH 2.0 distilled water showed 85% suppression, whereas in spent growth liquor this value was 95%. The optimum bacterial density was 3.25 × 1010 cells/g pyrite in 230-ml distilled water (2% pulp density) in the Hallimond tube. The degree of suppression by the cells was related to particle size but not to pH or temperature. The sulphur content of a synthetic coal/pyrite mixture was reduced from 10.9 to 2.1% by flotation after bacterial preconditioning. It is postulated that pyrite removal in coals which are cleaned by froth flotation could be significantly reduced using a bacterial preconditioning stage with a short residence time of 2.5 min.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260300102
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The effect of mixer design on the efficiency of a pump-mix mixer-settler (1961)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 7 (1961), S. 72-77 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The mixing efficiency of simple and pitched paddles, marine propellers, and centrifugal and disk impellers was determined by a heat transfer method in a single stage of a large pump-mix mixer-settler. The mixing devices were from 3 to 5 in. in diameter and were tested with a refined kerosene as the organic phase and water as the aqueous phase.A heat conductance was calculated from flow parameters and the efficiency and was correlated against impeller design and speed variables. For centrifugal and disk impellers UA was proportional to n1.2L3b0.3; for the paddles UA was proportional to n1.67L2.5b0.42. At normal operating speeds controlled variation of the internal recirculation of mixed phases through a centrifugal impeller did not change the efficiency.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690070118
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Rapid assessment of weathering stability from exposure of polymer films. III. Relative weathering stability of ABS and arylon, a related polymer blend (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 1181-1185 
    Details
    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: Arylon, a blend of an aromatic polysulfone and a terpolymer of acrylonitrile-butadiene and α-methylstyrene, weathers similarly to ABS. However its first-order rate constant for the loss of unsaturation is only 0.39 cm2(Wh)-1 as against 0.80cm 2(Wh)-1 for ABS. This slower weathering is probably caused by the decrease in light intensity penetrating Arylon compared with ABS as a result of the high degree of light scattering observed in the former.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1974.070180416
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Rapid assessment of weathering stability from exposure of polymer films. I. Real and simulated weathering of commercial ABS terpolymers (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 1159-1171 
    Details
    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: Changes in the infared transmission spectra of thin films were used to follow the natural and artificial weathering of ABS terpolymers. Photo-oxidation of the polybutadiene moiety, which is the major process involved, occurs only after a well-defined amount of ultraviolet energy has been absorbed. Therafter, unsaturation decreases in a first-order manner with respect to UV energy absorbed. Under artificial conditions with constant UV intensity, energy absorbed is synonymous with time, but this is not so in natural exposure because of the variability of solar energy and its UV content. The method permits rapid comparison of commercial grades of ABS with the advantage of using natural conditions. It has been shown that pigmentation (3.6 phr brown and 1.25 phr carbon black) increases weathering stability two- and fourfold respectively, as assessed by induction energy and rate of disappearance of unsaturation.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1974.070180414
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Evaluation of the hydrocarbon condensation polymerisation reaction by means of model compounds. I. The reaction with n-alkyl-bromides (1972)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 152 (1972), S. 121-132 
    Details
    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: Die Bildung von Copolymeren durch Reaktion von α-Methylstyrol (M) in Tetrahydrofuran mit Lithium in Gegenwart von Dihalogenalkanen (RX2) wird beschrieben. Der Einfluß der experimentellen Parameter auf die Struktur der Copolymeren wird untersucht, wobei das Dihalogenid durch das entsprechende Monohalogenid ersetzt ist. Die Untersuchung beschränkt sich auf n-Alkylbromide. Die relativen Mengen an HR-RH und HRMnRH mit n = 1, 2 und 3 wurden gaschromatographisch bestimmt. Es wurde gezeigt, daß die Reaktion diffusionkontrolliert abläuft und daß die Geschwindigkeit der Lithium-oberfläche proportional ist. Bei einem molaren Ausgangsverhältnis von Monomerem zu Monohalogenid von 1 : 1 (entsprechend einem Verhältnis von 2 : 1 für das SystemMonomeres/Dihalogenid) wurden ca. 90% HRM2RH gefunden. Dies zeigt, daß unter den gegebenen Bedingungen ein sehr einheitliches Copolymeres mit der vorherrschenden Sequenz [M-M-R] entsteht. Das System ist sehr empfindlich gegenüber einer Änderung des Ausgangsverhältnisses der Komponenten. Geringe Abweichungen vom molaren Verhältnis 1 : 1 bewirken eine starke Verringerung der Ausbeute an Dimeren.
    Notes: The title polymerisation involves the reaction in tetrahydrofuran of α-methylstyrene (M) with lithium in the presence of an alkyl dihalide (RX2) to form copolymers. This paper describes a method of studying the effect of changing the experimental parameters on the structure of these copolymers by replacing the dihalide with the corresponding monohalide (HRX). The study is confined to n-alkyl bromides and the relative amounts of the molecules HR-RH and HRMnRH (where n = 1, 2, and 3) have been determined by g.l.c. By this means it is shown that the reaction is diffusion controlled and the rate proportional to lithium surface area. At 1 : 1 monomer : monohalide stoichiometry (equivalent to 2 : 1 monomer : dihalide in the polymer system) the product is ∼ 90% HRM2RH indicating that the copolymer under these conditions is highly regular with the repeat unit [M-M-R] predominating. The system is extremely sensitive to the reactant ratio and small deviations from stoichiometry result in significant reductions in dimer yield.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1972.021520113
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Evaluation of the hydrocarbon condensation polymerisation reaction by means of model compounds. II. The reaction of with n-alkyl chlorides and iodides, and sec- and tert-alkyl bromides (1972)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 152 (1972), S. 133-142 
    Details
    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: Die Darstellung von Copolymeren durch Reaktion von α-Methylstyrol (M) in Tetrahydrofuran mit Lithium in Gegenwart von Dihalogenalkanen (RX2) wird untersucht. Die Verwendung von Monohalogenalkanen (RX) führt zu kleinen Molekülen, deren Mengenverhältnisse über den Polymerisationsprozeß und die Struktur der Copolymeren Aufschluß geben. Diese Arbeit beschreibt die Ergebnisse bei Verwendung von n-Alkyljodiden, -chloriden und sec- und tert-Bromiden.n-Alkyljodide verhalten sich ähnlich wie n-Alkylbromide (Teil I). Beim molaren Verhältnis 1 : 1 von Monomeren: Halogenid wird das Dimere HRM2RH in hohen Ausbeuten erhalten. n-Alkylchloride dagegen geben zahlreiche zusätzliche Produkte unter diesen Bedingungen. Die Analyse ihrer Struktur zeigte, daß sie durch Reaktion mit n-Alkyllithium entstehen, das seinerseits durch Reaktion des n-Alkylchlorids mit Lithium gebildet wird. Das unterschiedliche Reaktionsverhalten der Halogenide wird durch die relativ hohe Bindungsstärke der C-Cl-Bindung erklärt. Hieraus folgt, daß Copolymere, die mit Dichloriden als einer Komponente dargestellt werden, weniger einheitlich aufgebaut sind als solche, die aus Dibromiden gewonnen werden. sec- und tert-Bromide führen ebenfalls zu sahlreichen Produkten bei äquimolarem Umsatz mit α-Methylstyrol. Es konnte gezeigt werden, daß dies auf die β-Elirninierung von Wasserstoff zurückzuführen ist. Bei tert-Bromiden tritt die Wasserstoff-Eliminierung am deutlichsten auf, die zu 60% für den Abbruch des Dimeren verantwortlich ist.
    Notes: The title polymerisation involves the reaction in tetrahydrofuran of α-methylstyrene (M) with lithium in the presence of an alkyl dihalide (RX2) to form copolymers. Replacement of the dihalide by the analogous monohalide RX gives small molecules, the relative amounts of which furnish information on the polymerisation process and the resulting structures of the copolymers. This paper describes the use of n-alkyl iodides and chlorides, and sec- and tert-bromides in this regard.n-Alkyl iodides were found to behave in a similar manner to n-alkyl bromides (Part I) with high yields of the dimer HRM2RH being obtained at 1 : 1 M stoichiometry. On the other hand, n-alkyl chlorides gave a variety of additional products under these conditions and a structural analysis of these materials showed that they resulted from reactions involving n-alkyl lithium which was formed by the chloride reacting directly with the lithium. This difference in behaviour is explained in terms of the high strength of the carbon-chlorine bond and implies that copolymers prepared with dichlorides are less regular than those obtained with dibromides.sec- and tert-bromides also gave a variety of products at equimolar stoichiometry and this was shown to be due to the β-hydrogen elimination reaction becoming significant. Elimination was most prominent with the tert-bromides, accounting for about 60% of der termination reaction of the dimer.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1972.021520114
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Degradation of polytetramethylene oxide. I. Thermally-inducedPresented at the 148th American Chemical Society Meeting, Chicago, Illinois, September, 1964. (1965)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 81 (1965), S. 38-50 
    Details
    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: Es wurde der thermische Abbau von Polytetramethylenoxid untersucht. Das Polymere enthielt schwache Bindungen, die beim Erwärmen auf 50 bis 150°C leicht spalteten. In Xylol betrug die Aktivierungsenergie dieses Abbauvorganges 13,3 Kcal/Mol. Wie nachgewiesen wurde, sind die schwachen Bindungen Hydroperoxidgruppen, die sich in Gegenwart der Luft bildeten. Diese Gruppen konnten beim Erhitzen im Vakuum zerstört werden; der sich einstellende Abbaugrad des Polymeren hängt von der Zahl der vorhandenen Hydroperoxidgruppen ab. Messungen der Intrinsic-Viskosität des von schwachen Bindungen befreiten Polytetramethylenoxids zeigten eine regellose Kettenspaltung bei erhöhten Temperaturen, die nach der Gleichung verlief: \documentclass{article}\pagestyle{empty}\begin{document}$$ \log \rm{ }\left[ \eta \right] = - \alpha \cdot \rm{log \ (t } + \rm{ t}_0 )\rm{ } + \rm{ C} $$\end{document} Der Exponent α der KUHN-HOUWINK-Gleichung wurde für das Polymere in benzolischer Lösung und bei 20 °C zu 0,75 bestimmt. Die Analyse der Molekulargewichtsänderungen während des Abbaus bei verschiedenen Temperaturen ergab, daß die Kinetik der Kettenspaltung erster Ordnung war und durch folgende Geschwindigkeitsgleichung erfaßt wurde: \documentclass{article}\pagestyle{empty}\begin{document}$$ \rm{k} = 1,98 \cdot 10^{17} \rm \ { e}^{ - 49700/\rm{RT}} $$\end{document} Dieses Ergebnis wurde mit den Aktivierungsenergien der in Luft und unter Vakuum durchgeführten thermogravimetrischen Analyse verglichen.
    Notes: The thermal degradation of polytetramethylene oxide has been examined in detail. The polymer contained weak links which led to facile chain scission on heating. (50 to 150°C.). The activation energy of this degradation process in xylene solution is 13.3 Kcal/mol. The available evidence indicates that the weak links are hydroperoxide groups formed in the presence of air. These groups could be destroyed by heating in vacuum, the resultant degree of degradation of the polymer depending on the number of hydroperoxide groups present.Measurements of the intrinsic viscosity of polytetramethylene oxide, freed from weak links, showed that the polymer underwent random chain scission at elevated temperatures according to the equation: \documentclass{article}\pagestyle{empty}\begin{document}$ \log \left[ \eta \right] = - \alpha \ {\rm log \ (t} + {\rm t}_0 )\ + {\rm C} $\end{document} The exponent, α, of the KUHN-HOUWINK equation was thus determined to be 0.75 for the polymer in benzene at 20°C. Analysis of the molecular weight changes occurring during degradation at various temperatures showed that the chain scission process obeyed first order kinetics and could be expressed by the rate equation: \documentclass{article}\pagestyle{empty}\begin{document}$ \rm {k} = 1.98 \cdot 10^{17} \rm {e}^{ - 49,700/\rm{RT}} $\end{document} This result is compared with activation energies obtained by thermogravimetry in air and vacuum.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1965.020810104
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    The electron irradiation stability of polysulphone (1969)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 129 (1969), S. 63-72 
    Details
    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: Verglichen mit anderen Polymeren, sind Polysulfone gegenüber Bestrahlung mit Elektronen besonders beständig, wie hier gezeigt werden konnte. Das äußert sich in der Erhaltung mechanischer Eigenschaften wie der Biegefestigkeit und des Moduls, selbst nach Dosen von 200 Mrad.Dennoch erzeugt die Bestrahlung mit Elektronen tiefgreifende Änderungen in der chemischen Struktur. Das Molekulargewicht des Polymeren steigt, und es geliert nach 80 Mrad. Dosen größer als 200 Mrad geben einen konstanten Gelgehalt von 70%, woraus folgt, daß sowohl Spaltungs- als auch Vernetzungsvorgänge wichtig sind. G-Werte für Spaltung und Vernetzung wurden mit 0,08 bzw. 0,16 bestimmt.Die Entfärbung von Diphenylpikrylhydrazyl-Lösungen durch Lösungen von bestrahltem Polysulfon zeigten das Anwachsen von Gruppen mit aktivem Wasserstoff. Diese wurden als phenolische Gruppen erkannt.Der medrige G-Wert für das Gesamtgas (0,01) zeigt die Beständigkeit des Polysulfons an, aber die Zusammensetzung des Gases legt nahe, daß die drei Brückenbindungen zwischen den Phenylenringen, nämlich die Sulfon-, Äther- und Isopropylidenbrücke, durch die Bestrahlung angegriffen werden. Mögliche Reaktionen dieser Brückenbindungen und Vorgänge, welche die experimentellen Beobachtungen erklären, werden vorgelegt und erörtert.
    Notes: It has been shown that polysulphone is particularly stable to electron irradiation compared with other polymer systems. This was reflected in the retention of mechanical properties (flexural strength and modulus) even after doses of 200 Mrads.However electron irradiation produces significant changes in the chemical structure. The polymer increased in molecular weight and gelled after 80 Mrads. Doses greater than 200 Mrads gave a constant gel content of about 70 per cent indicating that scission as well as crosslinking processes were important. G values for scission and crosslinking were calculated to be 0.08 and 0.16 respectively.The discolouration of diphenyl picryl hydrazyl solutions by solutions of irradiated polysulphone indicated the accumulation of groups containing an active hydrogen. These groups were deduced to be phenolic.The low G value for total gas (0.01) indicates the stability of polysulphone but the gas composition suggests that the three linkages, sulphone, ether and isopropylidene between the phenylene rings are affected by irradiation. Possible reactions involving these linkages and the processes which may account for the experimental observations are advanced and discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1969.021290106
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...