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  • Springer Nature  (15)
  • Wiley-Blackwell  (12)
  • 1965-1969  (10)
  • 1960-1964  (14)
  • 1950-1954  (3)
  • 1
    Digitale Medien
    Digitale Medien
    Ultrasonic degradation of sol rubber in solution (1964)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 8 (1964), S. 2653-2659 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Sol rubber dissolved in three solvents - cyclohexane, petroleum ether (40-60°C. fraction), and toluene - was degraded by ultrasonic waves, the degradation kinetics being followed by measuring spectrophotometrically the consumption of the free radical scavenger α,α′-diphenyl-β-picryl hydrazyl. The kinetic data have been examined by the rate equations developed from two different approaches: one by Jellinek and the other by Ovenall. It has been observed that the number of bonds broken as a function of time can be fitted equally well by both equations in the initial stage, but as the time of degradation increases, especially when the number-average degree of polymerization attains a value less than 3Pe/2, the rate can be described better by Jellinek's equation than that of Ovenall. The rate constants K and the final degree of polymerization for rubber are found to depend on the nature of the solvent.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1964.070080613
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  • 2
    Digitale Medien
    Digitale Medien
    Viscometric determination of molecular weight of cellulose pulps in zinc ethylenediamine solutionCommunication No. 473 from the National Chemical Laboratory, Poona-8, India. (1963)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 7 (1963), S. 181-186 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A convenient method of preparing zinc ethylenediamine complex (ZED) solution for use as solvent for cellulose pulp is described, and the advantages in using this solvent (0.25M zinc in 41% ethylenediamine in water) over cupriethylenediamine (CED) or cuprammonium solutions for viscometric determination of molecular weight of cellulose are indicated. Intrinsic viscosities of eight rayon-grade pulp solutions have been determined at four temperatures: 15, 20, 25, and 30°C. The constants K = 5.85 × 10-5 and a = 0.936 of the Mark-Houwink equation [η] = KMna, required for evaluating the molecular weight of cellulose pulps in ZED solution, have been determined by using the molecular weight values obtained from CED solutions.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1963.070070116
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  • 3
    Digitale Medien
    Digitale Medien
    A study on the thermal degradation of rubber in dilute solutionsCommunication No. 529 from the National Chemical Laboratory, Poona-8, India. (1963)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 7 (1963), S. 2199-2209 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The kinetics of low-temperature (60-100°C.) thermal degradation of deproteinized and deresinified petroleum ether soluble fraction of natural rubber in two chemically inert solvents, cyclohexane and trans-decalin, have been studied. The changes in Mw, A2, and (r2)1/2 at various stages of degradation have been obtained from the lightscattering data. The rate constants and the energy of activation for chain scission have been calculated from the observed variation in Mu. The scission has been found to be random and the average energy of activation is 25.8 kcal./mole. This low-energy requirement suggests the presence of weak links in the rubber molecule which get ruptured at low temperature.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1963.070070619
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  • 4
    Digitale Medien
    Digitale Medien
    Ultrasonic degradation of macromolecules in solution. Study of degradation kinetics by estimation of free-radical scavenger DPPH and solution viscosity measurementsProd. No. 1357 (1966)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 10 (1966), S. 1089-1098 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The kinetics of degradation of butyl rubber in two solvents, cyclohexane and toluene, was studied by two independent techniques: viscosity measurements and free-radical estimation as a function of DPPH consumed. The general shape of the rate curves in the two cases is similar, but not identical. The rate given by estimation of DPPH is faster than that obtained from solution viscosity data. This has been attributed to the inherent limitations of the two methods for the quantitative determination of the number of breaks occurring in the polymer molecules. The rate is also reduced as the viscosity of the solution medium is increased, which may be correlated with the reduction of the cavitation effect responsible for degradation. The degradation rates in two solvent media initially having the same viscosity were unequal. This may be due to different solvent-solute characteristics, which means that the viscosity and cavitation change to different extents in the two cases throughout the course of degradation. The limiting degree of Polymerization (DP)∞ obtained after prolonged irradiation has been found to be dependent on parameters such as intensity of irradiation, solution viscosity, and initial DP of the molecules.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1966.070100801
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  • 5
    Digitale Medien
    Digitale Medien
    Rapid analysis of some coinage, jewellery, aluminium bronze and ternary alloys by the ring oven technique (1965)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 28 (1965), S. 137-140 
    Details
    ISSN: 0021-8383
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Schemes have been worked out for the quantitative separation and subsequent determination of the constituents in a number of alloys containing Au—Cu, Cu—Al, Fe—Au and Fe—Cu—Al by the ring oven technique. Gold is migrated to the ring zone by extraction with n-butanol at pH = 1.5 and iron or copper with acetylacetone. Aluminium is moved to the ring zone by acidified ethanol.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/prac.19650280306
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  • 6
    Digitale Medien
    Digitale Medien
    Coulometric Determination of Arsenic(III) and antimony(III) (1963)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 21 (1963), S. 147-148 
    Details
    ISSN: 0021-8383
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The coulometric determination of tripositive arsenic and antimony by electrogenerated iodine in a NaHCO3 buffered solution of pH 8 has been described. The end point can be determined visually using starch as an indicator. Quantities of As(III) and Sb(III) down to the microgram level can be determined within permissible limits of error.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/prac.19630210304
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  • 7
    Digitale Medien
    Digitale Medien
    Studies on light scattering by polymethyl methacrylate solutions (1954)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 13 (1954), S. 461-469 
    Details
    ISSN: 0022-3832
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The scattering of light by solutions of a well-fractionated sample of polymethyl methacrylate in acetone, methyl ethyl ketone, and benzene, have been measured using 4358 and 5461 A. wave lengths as incident radiations. The average molecular weights of the polymer from turbidity measurements and lengths determined from angular dissymmetries of scattered light are 571,000 and 760 A. in acetone, 38,400,000 and 715 A. in methyl ethyl ketone, and 408,000 and 375 A. in benzene. The abnormal molecular weight observed in methyl ethyl ketone solution may be ascribed to low μ - μ0 value of the medium. The greater molecular extension in ketone than in benzene solutions is explained in terms of the relative magnitudes of solute-solvent interaction. The depolarization ratios ρu, ρv and ρh have been measured and the decrease of ρv and ρh with increase in concentration of the polymer in ketonic solvents and little change under similar conditions in benzene, are discussed in the light of the “molecular field effect” of Gans.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1954.120137105
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  • 8
    Digitale Medien
    Digitale Medien
    Polymerization of N-vinylearbazole with vanadium compounds. Part I. Polymerization with vanadium pentoxide and metal vanadates (1969)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 124 (1969), S. 263-273 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: In Gegenwart von Vanadiumpentoxid als heterogenern Katalysator Wurde N-Vinylcarbazol (NVC) in Substanz polymerisiert. Die Polymerisationsgeschwindigkeit hängt vom Verhältnis des Katalysators zum Monomeren ab. Es wurde ein kationischer Reaktionsmechanismus vorgeschlagen, und es wurde versucht, die Rolle der V2O5-Oberfläche bei der Polymerisation aufzuklären. Es wird vermutet, daß die π-Säureeigenschaft des V5⊕-Ions bei der Initiierung der Polymerisation miteinbezogen werden muß.Die Wirkung einer Anzahl von Zusätzen auf die Polymerisationsgeschwindigkeit wurde untersucht; das Ergebnis bekräftigt die Annahme eines kationischen Verlaufs.Es wurde auch die katalytische Wirksamkeit einer Anzahl von Metallvanadaten bei der Polymerisation von NVC untersucht. Es ergab sich eine hinreichend gute Bezichung zwischen der katalytischen Wirksamkeit und dem elektronegativen Charakter des metallischen Bestandteils.
    Notizen: Bulk polymerization of N-Vinylcarbazole (NVC) has been carried out using vanadium pentoxide as the contact catalyst. The rate of polymerizatlon has been found to depend upon catalyst to monomer ratio. A cationic mechanism has been suggested and the role of V2O5 surface in the polymerization has been tentatively analyzed. The π-acid characteristies of V5⊕ ion is believed to be involved in initiating the polymerization. The effect of a number of additives on the polymerization rate has been studied, which endorses the cationic mechanism. The catalytic efficiency of a number of metal vanadates for the polymerization of NVC has also been studied. A fairly good correlation between the activity and electronegativity of the metallic moiety has been established.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1969.021240127
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  • 9
    Digitale Medien
    Digitale Medien
    Interaction of polylysine with phosvitin and nucleic acids (1969)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 124 (1969), S. 113-117 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die DNS-abhängige RNS-Synthese wird durch basische Proteine, wie Histone oder Polylysin, gehmmt: es wurde gefunden, daß dieser Hemmungseffekt durch Phosvitin, ein phosphoprotein, aufgehoben wird. Turbidimetrische Untersuchungen ergaben, daß Polylysin mit DNS iind RNS in stöchiometrischem Verhältnis reagiert.Es wird angenommen, daß diese Reaktion mit DNS die Ursache des Hemmungseffektes ist. Noch wirksamer als DNS reagiert Phosvitin mit Polylysin. Phosvitin kann in viel geringerer als der stöchiometrischen Menge mit DNS um Polylysin konkurrieren, also DNS freisetzen und als Matrize für die RNS-Synthese verfügbar machen. Phosphoserin ist, im Gegensatz zu Phosvitin, unwirksam bei der Aufhebung des Hemmungseffektes von Polylysin.
    Notizen: DNA dependent RNA asynthesis in inhibited by basic proteins like histones or polylysine This inhibitory effect is found to be suppressed by phosvitin, which is a phosphoprotein. Turbidometric studies indicate that polylysine interacts with DNA and RNA stoichiometrically. This interaction with DNA has been thought to be the cause of this inhibitory effect. Phovitin also interacts with polylysine more effectively than DNA. Phosvitin in quantities much less than the stoichionietric amount can compete with DNA for the polylysine and can thus make DNA free and available as template for the RNA synthesis. Phosphoserine, unlike pbosvitin, is ineffective in suppressing the inhibitory effect of polylysine.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1969.021240112
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  • 10
    Digitale Medien
    Digitale Medien
    Über Andrographolid (1951)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 34 (1951), S. 652-677 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Die vorliegende Arbeit befasst sich mit der Konstitutionsaufklärung des Andrographolids, eines Bitterstoffes der indischen Medizinalpflanze Andrographis paniculata Nees. Verschiedene, in der früheren Literatur vorkommende Widersprüche und Unstimmigkeiten konnten dabei abgeklärt werden.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19510340229
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