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
    Human exposure to styrene (1976)
    Springer
    International archives of occupational and environmental health 37 (1976), S. 47-55 
    Details
    ISSN: 1432-1246
    Keywords: Phenylglyoxylic acid ; Gaschromatography ; Diazomethane derivatization of phenylglyoxylic acid ; Styrene metabolites ; Urinalysis of styrene metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The derivatization of phenylglyoxylic acid (PGA), a urinary styrene metabolite, gives with diazomethane under ordinary reaction conditions secondary products as expected from the behaviour of other α-keto acids. Thus reproducible quantitative analysis becomes difficult. It is shown that by proper selection of reaction conditions (low temperature, short reaction time) these secondary transformations can be inhibited and exclusive derivatization to the methylester is obtained. A quantitative determination of urinary PGA can be based on this derivatization procedure. However, this method is not considered suitable for routine monitoring due to the delicate reaction conditions necessary. The results are discussed with reference to a recently published procedure based on an unknown derivative of PGA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409363
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Human exposure to styrene (1976)
    Springer
    International archives of occupational and environmental health 37 (1976), S. 57-64 
    Details
    ISSN: 1432-1246
    Keywords: Mandelic acid ; Phenylglyoxylic acid ; Gaschromatography ; Styrene metabolites ; Urinalyses of styrene metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A simple and specific method for the quantitative gaschromatographic (GC) analysis of mandelic and phenylglyoxylic acid (MA and PGA), human urinary styrene metabolites, is described. MA is determined by trimethylsilylation and subsequent GC analysis. Because of difficulties involved in the direct determination of PGA due to the lack of quantitative and reproducible derivatization methods, this acid is reduced to MA prior to GC analysis. By a double determination with and without reduction both acids can be analyzed quantitatively. Both analysis show the same accuracy and precision and can therefore be intercorrelated accurately.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409364
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Großvolumige Verschleißbauteile aus plattierten Grobblechen (1996)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 27 (1996), S. 618-621 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Plated steel sheets are increasing used for the manufactoring of heavy wear components. The analysis of wear allows to determine beforehand the wear charakteristic of plated steel sheets and to reach statements about the optimal inset possibilitys of the component parts.
    Notes: Plattierte Grobbleche werden zunehmend für die Fertigung großvolumiger Verschleißbauteile verwendet. Die Verschleißuntersuchungen dienen dazu, das Verschleißverhalten plattierter Grobbleche besser vorherzubestimmen und somit Aussagen über die optimalen Einsatzmöglichkeiten der Bauteile zu treffen.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19960271220
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Energy transfer in polymers and nitroxide decay during photolysis (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 24 (1986), S. 1651-1664 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: When polymeric materials doped with nitroxides of the 2,2,6,6-tetramethylpiperidine type are exposed to light, the nitroxide concentration decreases. The two mechanisms for the decrease of the nitroxide are the reaction of nitroxide with free radicals produced during photolysis of the polymer to form amino ethers and the abstraction of hydrogen atoms by excited-state nitroxides to form hydroxyl amines. Excited-state nitroxides can be formed in two ways: by direct absorption and by energy transfer. In this paper, the effect of energy transfer on the rate of decay of the nitroxide signal is studied, and measurements of nitroxide decay are used to probe energy transfer in crosslinked polymeric coatings. A simple kinetic scheme is used to interpret nitroxide decay during photolysis of both solutions and polymers containing benzophenone. These results are used to show that the slope of the line relating nitroxide decay rate to nitroxide concentration is essentially determined by energy transfer from a coating-based chromophore to nitroxide. The nitroxide decay assay is also used to study the effectiveness of a benzotriazole ultraviolet light absorber as a quencher.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1986.090240802
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Degradation of organic coatings. I. Hydrolysis of melamine formaldehyde/acrylic copolymer films (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 3651-3662 
    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 hydrolysis of melamine formaldehyde crosslinked acrylic copolymer films has been studied using infrared spectroscopy. It has been found that during hydrolysis, crosslinks between the acrylic copolymer and the melamine crosslinker are broken and that crosslinks between melamine molecules are formed. The rate of hydrolysis depends on the following: (1) the type of crosslinker used (partially alkylated melamines hydrolyze faster than fully alkylated melamines); (2) the amount and strength of acid catalyst used and whether or not the catalyst can be extracted from the coating during hydrolysis; (3) the initial crosslink density; (4) the hydrolysis temperature. In some formulations, it can be expected that virtually all of the acrylic-melamine crosslinkes will be hydrolyzed. However, due to the formation of melamine-melamine crosslinks, the overall crosslink density does not necessarily decrease significantly as a result of this hydrolysis.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1982.070271002
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Crosslinking kinetics and network formation in organic coatings containing hexamethoxymethylmelamine (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 253-266 
    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: We have developed a kinetic model of the crosslinking reaction of hydroxy-functional acrylic copolymers with fully alkylated melamines. This model accurately describes the extent of the crosslinking reaction as a function of cure time and melamine concentration in coating films. Using this model, we have determined the effects of acid catalyst concentration and strength and the effects of cure temperature on the rate constant of the crosslinking reaction. The rate constant is proportional to the catalyst concentration and to the square root of the acid constant of the catalyst. The temperature dependence of the rate constant follows an Arrhenius rate law with an activation energy of 12.5 kcal/mol independent of catalyst type. Amine salts of p-toluenesulfonic acid have been compared with p-toluenesulfonic acid as catalysts in these coatings at different bake temperatures. These kinetic results have been used in a network structure model to calculate the cure response of these coatings as a function of formulation variables.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1983.070280122
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Characterization of solutions and aqueous dispersions of epoxy/amidoamine resins (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 34 (1987), S. 2313-2323 
    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: Molecular weight advancement and epoxy conversion in epoxy-amidoamine resins have been characterized in solutions and in aqueous dispersions using viscosity, light scattering, and near-infrared spectroscopy. By measuring the intensity of the 4532 cm-1 band in the near infrared, it is possible to determine the concentration of epoxy groups in these resins at low levels in the presence of amine and acid groups as well as solvents and other species. The epoxy-amine reaction in these resins is found to be second order with an activation energy of around 13 kcal/mole. The addition of one mole of carboxylic acid per mole of amine functionality was sufficient to quench the epoxy-amine reaction. Preparation of aqueous dispersions suitable for electrocoat formulation required that the extent of epoxy reaction be within a given range. Although the addition of acid completely quenched the epoxy-amine reaction, a slow side reaction was discovered which consumes epoxy groups and ultimately changes the physical properties of coatings made from these dispersions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070340621
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Crosslinking chemistry and network structure in organic coatings. II. Effect of catalysts on cure of melamine formaldehyde/acrylic copolymer films (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 18 (1980), S. 2015-2025 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In a previous paper, the extents of reaction of various functional groups in different acrylic copolymer melamine-formaldehyde crosslinked formulations were measured by infrared spectroscopy. From these data and a statistical model, various network structure parameters could be calculated. One of these, effective crosslink density, was found to correlate well with film solvent resistance. In this paper the effects of the addition of strong acid catalysts on cure chemistry and network structure are determined. Both solvent-based and water-based formulations have been studied. In the solvent-based formulations studied, the addition of acid catalysts greatly enhanced the crosslinking reactions at low temperatures and dramatically lowered the cure temperature. Acid catalysts also lowered the cure temperature of a water-based formulation based on a high (180°C) cure temperature melamine. In contrast, the addition of acid catalysts had a negligible effect on the cure chemistry of a water-based formulation crosslinked with a low (130°C) cure temperature melamine. For this case the rate limiting process was found to be the rate of removal of neutralizing amine from the film. Cure temperatures in this system could only be lowered by replacing the amine used with a more volatile amine.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.180181002
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Magic-angle 13C-NMR of cured and degraded acrylic copolymer/melamine formaldehyde coatings (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 22 (1984), S. 2009-2020 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Magic-angle carbon-13 NMR has been used to probe the structure and dynamics of acrylic copolymer melamine formaldehyde crosslinked coatings. Changes in chemical composition that occur in conventional accelerated weathering tests were found to be dominated by hydrolysis of acrylic-melamine crosslinks and subsequent formation of melamine-melamine crosslinks. Evidence for photo-oxidation was also observed. These results are in substantial agreement with infrared measurements also made on these coatings. Gated high-power decoupling experiments were used to determine relative mobilities of the different carbon resonances as a function of acrylic copolymer composition and as a function of degradation. It was found that motion of the side-chain carbons on the acrylic copolymer was not sensitive either to the chemical composition of the coating or to the extent of degradation. Mobilities of the main-chain carbons of the acrylic copolymer decrease with increasing glass transition temperature of the acrylic copolymer. For acrylic copolymers containing styrene, it is found that the main-chain carbon mobilities decrease with weathering. The melamine triazine ring becomes very rigid after degradation consistent with the formation of short melamine-melamine crosslinks.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.180221202
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Crosslinking chemistry and network structure in organic coatings. I. Cure of melamine formaldehyde/acrylic copolymer films (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 18 (1980), S. 1997-2014 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Crosslinking chemistry and network formation in hydroxy and carboxy functional acrylic copolymer resins cured with representative melamine-formaldehyde crosslinking agents have been studied by infrared spectroscopy. Network formation in these systems is dominated by two reactions, the condensation of the hydroxy (or carboxy) functionality of the acrylic resin with melamine alkoxy groups to form acrylic-melamine crosslinks, and the condensation of melamine hydroxy groups to form melamine-melamine crosslinks. The extents of these reactions have been studied as functions of acrylic resin composition, melamine type and concentration, and cure time and temperature. For melamines with just methoxy functionality, the extent of formation of acrylic-melamine crosslinks increased steadily with cure temperature. For melamines with substantial hydroxy functionality, the extent of formation of acrylic-melamine crosslinks increased rapidly then leveled off with increasing cure temperature. The formation of melamine-melamine crosslinks increased slowly with increasing cure temperature. From these data and a statistical model, effective crosslink densities were calculated. The crosslink densities correlated well with solvent resistance.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.180181001
    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...