ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

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
    ISSN: 0959-8103
    Keywords: TGDDM ; mPDA ; carbon powder ; cure kinetics ; rheology ; 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 tetraglycidyl 4,4′-diaminodiphenylmethane (TGDDM) type tetrafunctional epoxy resin containing carbon powders was cured with the stoichiometric amount of a tetrafunctional curing agent, namely m-phenylenediamine (mPDA). Carbon powders were oxidised with air or nitric acid. The influence of carbon powders on curing of the resin was followed by dynamic mechanical analysis, Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Gelation and vitrification times were determined as a function of the variations of dynamic properties. The evolution of viscoelastic modulus during curing of the different mixtures showed that untreated carbon powder clearly accelerated the kinetics of curing whilst oxidation of carbon powders could remove their catalysing effect. These results were confirmed by monitoring the changes in conversion of epoxy and amine groups during cure using the FTIR technique. DSC experiments also showed the influence of carbon powder as a catalyst and the loss of the catalysing effect as a consequence of chemical treatment.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    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 rheological behavior of a tetraglycidyl diaminodiphenyl methane with a tetrafunctional aromatic diamine has been studied in terms of the influence of curing agent content and temperature. In this work, critical times corresponding to gelation are used as a measure of activation energy. The dynamic mechanical behavior has been used to analyze the curing extent of these epoxy systems with different amine contents before and after thermal posttreatment. The β-relaxation peak temperature is found to increase with the curing agent content and also after thermal posttreatment. This has been related to the rise of crosslinking extent. Dependence of flexural mechanical properties on curing agent content and the postcure process has also been determined.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    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 diglycidyl ether of bisphenol-A-type difunctional epoxy resin was cured with different amine-type curing agents at stoichiometric ratios. The crosslink process was followed by viscosimetry and differential scanning calorimetry. The gelation time and the apparent activation energy were found to be strongly dependent on the structure of the hardener. The heat of reaction did not vary significantly when the hardener was changed. An interpretation based on structural aspects such as amine reactivity, steric hindrance, and chain rigidity is proposed for the variations corresponding to the curing process. Master viscosity curves have been built up for all mixtures. The effect of the hardener on the glass transition temperatures of the different mixtures has been analyzed taking into account the crosslink density, measured by the rubber modulus obtained by dynamic mechanical studies, and the chemical structure of the hardener chains. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0887-6266
    Keywords: epoxy resins ; liquid modifiers ; cure schedule ; ultimate properties ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A diglycidyl ether of bisphenol-A (DGEBA) epoxy resin has been stoichiometrically cured with cycloaliphatic amine 4,4′-diamino-3,3′-dimethylcyclohexylmethane (3DCM) and modified with an amine terminated oligomer polyoxypropylenetriamine (POPTA) at a concentration of 15 wt %. Mixtures, postcured at the same temperature, have been precured at different temperatures. Phase separation takes place before gelation at all precure temperatures used. The variation in the glass transition region of the mixtures has been analyzed by dynamic mechanical measurements. Mechanical properties and fracture toughness of the modified mixtures have been related to their microstructural spherical features. Results are compared to those for the unmodified mixtures cured with different precure temperatures. © 1997 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 2018-12-19
    Description: The implementation and certification of QA systems has become a widespread practice in the business world. Measurement and control systems adopted by businesses should reflect their level of commitment to quality management. Generally speaking, the need to develop non-financial indicators supporting the implementation of QA systems and their subsequent continual assessment is generally accepted. This work studies the relationship between quality and the use of non-financial indicators to manage quality in the Spanish furniture industry. Our results allowed us to claim that ISO 9000 certified businesses use non-financial indicators to a larger extent compared to non-certified businesses.
    Keywords: ddc:330 ; measurement ; non-financial measures ; ISO 9000 ; quality management
    Repository Name: EconStor: OA server of the German National Library of Economics - Leibniz Information Centre for Economics
    Language: Spanish
    Type: doc-type:article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    facet.materialart.
    Unknown
    Vigo: Academia Europea de Dirección y Economia de la Empresa (AEDEM)
    Publication Date: 2018-11-16
    Description: The characteristics of the Board of Directors, its running and composition reflect, for most family firms, their structure of power, experience, interests and culture. The presence of outsiders in the board does not necessarily imply a loss of power by the family, as this will impair the transfer of the culture and values of the firm, the vision of the family and its strategic implementation. This work includes a series of recommendations on the most adequate way to integrate outsiders in family firms depending on the combination of ownership distribution and kind of management.
    Keywords: ddc:330 ; outsiders ; family firm ; board of directors
    Repository Name: EconStor: OA server of the German National Library of Economics - Leibniz Information Centre for Economics
    Language: Spanish
    Type: doc-type:article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2014-04-01
    Electronic ISSN: 2296-598X
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Frontiers Media
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Publication Date: 2014-10-08
    Description: The mass budget of the ice caps surrounding the Antarctica Peninsula and, in particular, the partitioning of its main components are poorly known. Here we approximate frontal ablation (i.e. the sum of mass losses by calving and submarine melt) and surface mass balance of the ice cap of Livingston Island, the second largest island in the South Shetland Islands archipelago, and analyse variations in surface velocity for the period 2007–2011. Velocities are obtained from feature tracking using 25 PALSAR-1 images, and used in conjunction with estimates of glacier ice thicknesses inferred from principles of glacier dynamics and ground-penetrating radar observations to estimate frontal ablation rates by a flux-gate approach. Glacier-wide surface mass-balance rates are approximated from in situ observations on two glaciers of the ice cap. Within the limitations of the large uncertainties mostly due to unknown ice thicknesses at the flux gates, we find that frontal ablation (−509 ± 263 Mt yr−1, equivalent to −0.73 ± 0.38 m w.e. yr−1 over the ice cap area of 697 km2) and surface ablation (−0.73 ± 0.10 m w.e. yr−1) contribute similar shares to total ablation (−1.46 ± 0.39 m w.e. yr−1). Total mass change (δM = −0.67 ± 0.40 m w.e. yr−1) is negative despite a slightly positive surface mass balance (0.06 ± 0.14 m w.e. yr−1). We find large interannual and, for some basins, pronounced seasonal variations in surface velocities at the flux gates, with higher velocities in summer than in winter. Associated variations in frontal ablation (of ~237 Mt yr−1; −0.34 m w.e. yr−1) highlight the importance of taking into account the seasonality in ice velocities when computing frontal ablation with a flux-gate approach.
    Print ISSN: 1994-0416
    Electronic ISSN: 1994-0424
    Topics: Geography , Geosciences
    Published by Copernicus on behalf of European Geosciences Union (EGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2014-07-01
    Print ISSN: 0961-9534
    Electronic ISSN: 1873-2909
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Process Engineering, Biotechnology, Nutrition Technology
    Published by Elsevier
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 2013-08-26
    Description: Frontal ablation from marine-terminating glaciers and ice caps covering the islands off the western coast of the Antarctic Peninsula is poorly known. Here we estimate the frontal ablation from the ice cap of Livingston Island, the second largest island in the South Shetland Islands archipelago, using glacier surface velocities obtained from intensity offset tracking of PALSAR-1 imagery and glacier ice thickness inferred from principles of glacier dynamics and calibrated against ground-penetrating radar (GPR) measurements of ice thickness. Using 21 SAR images acquired between October 2007 and January 2011, we obtain surface velocities of up to 250 m yr−1 and an average frontal ablation rate of about 509 ± 381 Mt yr−1, equivalent to a specific mass change of −0.7 ± 0.5 m w.e. yr−1 over the area of the ice cap (697 km2). A rough estimate of the surface mass balance of the ice cap gives 0.1 ± 0.1 m w.e. yr−1, resulting in a~total mass balance for Livingston Island ice cap of −0.6 ± 0.5 m w.e. yr−1. We find that frontal ablation and surface ablation contribute equal shares to total ablation. We also find large changes in frontal ablation rate (of ∼237 Mt yr−1) due to temporal variability in surface velocities. This highlights the importance of taking into account the seasonality in ice velocities when computing frontal ablation with a flux-gate approach.
    Print ISSN: 1994-0432
    Electronic ISSN: 1994-0440
    Topics: Geography , Geosciences
    Published by Copernicus on behalf of European Geosciences Union (EGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...