Library

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
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 15 (1990), S. 701-704 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: AES spectra, when measured in the constant ΔE/E mode, may be distorted by the varying efficiency of the electron detector, usually a channel electron multiplier (CEM). In the analogue mode, this is a problem that increases as the emitted electron energy falls below 200 eV. Instruments may be modified by adding transparent meshes and by biasing the front of the CEM by 200 eV. In this way, the spectral distortion may be reduced by a factor of 10 at 50 eV, so that the resultant spectral shape is within ±10% of the true shape over the energy range 25-2000 eV. This small distortion may be calibrated accurately so that true spectra may be derived from all modified instruments with greater reliability and confidence than in unmodified instruments.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 16 (1990), S. 168-172 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: As a result of careful calibration, a metrology spectrometer has been developed at the National Physical Laboratory (NPL) to give true spectra. This instrument has been used to measure the true spectra from three reference materials under defined conditions in AES. Measurements for these reference materials, on any other instrument, allow that instrument's intensity-energy response function to be calibrated so that that instrument, in turn, may produce true spectra. In a VAMAS interlaboratory assessment involving 38 respondees, these methods and data have been tested. The results show that AES instruments may be calibrated over the energy range 10-2500 eV to give true spectra to an accuracy in the range 1.5-3.0% in the direct mode and ∼12% in the differential mode. For the first time, all these instruments may be calibrated to give: (1) the same spectra; and (2) spectra in which the instrumental systematic intensity errors are reduced to the above levels.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 19 (1992), S. 175-180 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The application of the maximum entropy method to non-destructive depth profiling by angle-dependent XPS is described. The algorithm gives the set of depth profiles that has maximum Skilling-Jaynes entropy, subject to the condition that the calculated data agree with the measured data within the experimental precision. The method does not require an inverse transform, is robust to experimental noise and is not restricted to small numbers of components. The programme can determine which of a set of prior estimates for the depth profiles is most probable; however, the reconstruction near the surface is virtually independent of this choice. Further, the method also estimates the accuracy of the reconstruction from a single data set. It is illustrated using model data and by a re-analysis of angle-resolved XPS data sets available in the literature.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 16 (1990), S. 144-148 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A principal requirement for quantitative AES and XPS is the ability to measure true spectral intensities. In order to achieve this we have developed a fully instrumented electron spectrometer to measure absolute intensities for AES and XPS. The spectra contain no distortion due to the energy dependencies of the analyser transmission or the detector efficiency, and therefore provide the true spectrum n(E) with a known uncertainty. In addition, the intensity scale is known accurately in terms of electrons detected per unit of incident flux. The experimental methods and theoretical basis used in the determination of standard reference spectra are discussed, and results are presented for both Auger electron and x-ray photoelectron spectroscopies. AES or XPS spectra of NPL reference materials taken on any user's instrument, with the appropriate conditions, may be compared with the true spectra derived here to calibrate the energy dependence of that particular instrument's intensity scale. In this way, all instruments may be calibrated absolutely to an accuracy of ±2%.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Fire and Materials 15 (1991), S. 181-189 
    ISSN: 0308-0501
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The decay of HCl was investigated in two small-scale scenarios: pure HCl injection into a 31 chamber and combustion of plasticized PVC in a 2001 chamber. The effects investigated included (1) humidity, (2) temperature, (3) concentration of HCl and (4) wall material. Surface materials studied were PMMA, ceiling tile (front and back), Marinite, painted PMMA, unpainted gypsum board and cement. In view of the very rapid HCl decay in most of those surfaces, the effects were often examined with small ‘chips’ of materials in a PMMA chamber, with fresh walls for each experiment. Experiments were also carried out to investigate the effect of surface ageing, with painted gypsum board, painted PMMA and unpainted gypsum board walls. HCl decay is very fast in cement or unpainted gypsum board surface (almost impossible to saturate with HCl) and almost as fast on ceiling tile and Marinite. Saturation of HCl can be reached on painted gypsum board and painted PMMA surfaces, albeit at different rates. An earlier empirical model from mathematical fitting had been followed by a new HCl generation, transport and decay model, with a sound physical basis. This allowed calculations of parameters for all the surfaces used. Much work has already been done in devising and writing a zone model for use together with fire hazard models (particularly the NIST model, FAST) to calculate correct HCL concentrations in various fire scenarios. This work, which concludes the investigation of these two static fire scenarios for the surfaces analysed, represents one more step in the pursuit of that goal.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Fire and Materials 6 (1982), S. 99-110 
    ISSN: 0308-0501
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A review was made of smoldering fire experiments conducted in closed rooms and buildings. The results were summarized by tabulating maximum levels of CO, the time integral of CO concentration (‘dose’), CO2, temperature rise and oxygen consumption. A hazard time based on the attainment of a CO dose equal to 4.5% CO-minutes and the time for transition to flaming were also tabulated. The likelihood of reaching a critical CO condition during smoldering seems to be comparable with the likelihood of having transition to flaming occur. A theoretical model, requiring inputs of CO production rate and energy release rate, was executed and compared with available data. The theoretical results for CO concentration as a function of time were in good agreement with the experimental data. The model offers a means of extrapolating test data to compartments of various size in order to assess the general hazard of CO due to smoldering.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 1 (1979), S. 149-160 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A computer-controlled atom prove time-of-flight mass spectrometer system is described which permits quantitative microanalysis to be undertaken at the 1-2 nm level. Distinctive features of the system include the use of a Johnston detector, to give low noise, high gain and high detection efficiency; incorporation of a movable channel plate and screen assembly, to provide a variable aperture; and the development of a comprehensive set of computer plate and screen assembly, to provide a variable aperture; and the development of a comprehensive set of computer software, to assist in the processing of data and presentation of analytical results. The system has been used successfully in a number of metallurgical investigations. In this paper, particular attention is given to describing the operating conditions required to achieve optimum performances, and to discussing the questions of background noise reduction and the deconvolution of spectra. The quantitative analysis capability of the instrument is demonstrated by reference to the results obtained from a range of standard materials, including steels. Applications to problems of metallurgical interest are illustrated by the analysis of ultra-fine particles in a Cu/Co alloy, and the analysis of carbides and carbide-matrix interfaces in a 2¼Cr/1Mo steel. The spatial resolution obtainable under different operating conditions is discussed, and the particular problems involved in the study of interfaces by this technique are described in detail.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 3367-3381 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rutherford backscattering spectrometry (RBS) has been used to detect and quantitate the thallium concentration resulting from the thallous ethoxide derivatization of phenol and carboxylic acid groups contained in the surface region of bisphenol-A polycarbonate (PC) sheet. Hydrolysis of the PC surface prior to derivatization leads to increased thallium levels, in which the chemical nature of the thallium is shown to be of the form R-O-Tl (R = alkyl or aromatic) by electron spectroscopy for chemical analysis (ESCA). Similar trends in thallium concentrations were observed by both RBS and ESCA for PC surfaces that had been exposed for increasing lengths of time to accelerated weathering and outdoor Florida conditions. The detection limit for thallium in PC using RBS is ca. 5 × 1013 atoms/cm2. The diffusion of thallous ethoxide and transesterification of the aromatic carbonate linkage led to a thallium-containing layer 300-700 Å thick, which increased the experimental uncertainty when assaying residual uncapped polymer chains in unweathered material. During the course of the RBS analysis, the interaction of 2-MeV 4He+ with the PC substrate caused dramatic chemical and physical changes. Microscopy and profilometry indicate that a crater was formed having the same cross-sectional area as the incident ion beam with a depth (ca. 0.3-1.5 μ) that varied according to the beam energy and integrated charge. ESCA analysis provided evidence for the loss of the carbonate linkage and the appearance of carbonyl and ester groups. Infrared analysis of the crater bottom shows the appearance of O-H stretch, carbonyl functionality other than aromatic carbonate, and enhanced aromatic ring stretch vibrations. Crosslinking and subsequent densification of the polymer matrix are though to be responsible for the observed morphological changes. It is suggested that this beam-induced damage does not prohibit the use of RBS to measure high-Z elements on a PC matrix since quantitation of 1000-Å Au layers on silicon and PC gave identical results.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 159-170 
    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: Carbon dioxide sorption isotherms in poly(methyl methacrylate) (PMMA) and poly(ethyl methacrylate) (PEMA) are reported for pressures up to 20 atm. Temperatures between 35 and 80°C were studied for PMMA and temperatures between 30 and 55°C were studied for PEMA. Typical dual mode sorption isotherms concave to the pressure axis were observed in all cases. The measured Langmuir sorption capacities of both polymers extrapolated to zero at the glass transition (Tg) consistent with the behavior of other glassy polymer/gas systems. Sorption enthalpies for CO2 in the Henry's law mode for PMMA and PEMA are in the same range (-2 to -4 kcal/mole) as has been reported for a variety of other glassy polymers such as poly(ethylene terephthalate), polycarbonate, and polyacrylonitrile. Some of the data suggest that postcasting treatment of the PEMA films left a small amount of residual solvent in the film. the presence of the trace residual solvent during quenching from the rubbery to the glassy state after annealing appears to cause a dilation of the Langmuir capacity and an alteration in the apparent Langmuir affinity constant of the PEMA film. These results suggest the possibility of tailoring physical properties of glassy polymers such as sorptivity, permeability, impact strength, and craze resistance by doping small amounts of selected residuals into polymers prior to quenching to the glassy state from the rubbery state.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 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: A series of prepolymers containing terminal blocked isocyanate groups was prepared by reaction of isocyanate-terminated prepolymers [derived from a poly(propylene oxide) diol (MW = 2000) or a triol (MW = 3000) and different diisocyanates] with various blocking agents. Their curing rates with a polyepoxide crosslinking agent were measured to assess their suitability for a delayed-cure durable-press treatment for wool. The curing rates varied over a wide range, but commonly used blocking groups such as phenols, caprolactam, β-diketones, and alcohols were not sufficiently reactive for the intended application, although others, e.g., oximes and certain blocking agents containing a basic center such as N,N-diethylhydroxylamine, hydroxypyridines, and hydroxyquinolines, had the required reactivity. Blocking by 1,3-dipolar cycloaddition of nitrones was examined, but the reactivities were too low. Prepolymers containing blocked aromatic isocyanates were more reactive than those containing blocked aliphatic isocyanates. Difunctional butanone oxime-blocked pre-polymers cured slightly more slowly than analogous trifunctional prepolymers.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...