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  • 1
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 2299-2310 
    ISSN: 0887-624X
    Keywords: plasma ; x-ray photoelectron spectroscopy surface modification ; O3P ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas phase downstream products of an air glow discharge have been measured, using absorption and emission spectroscopies, as a function of plasma power, air flow rate, and distance from the plasma. In addition, the reaction of these products with a linear low density polyethylene (LLDPE) polymer surface has been followed using x-ray photoelectron spectroscopy (XPS). At higher air flow rates (〉300 sccm), the primary reactive species is confirmed to be O(3P) atomic oxygen. Some O(3P) is generated in the plasma itself, but more appears to be formed in the downstream region, because of dissociation of molecules in their excited states. At low flow rates, the concentration of O(3P) is strongly depleted at the sample position, but other atomic oxygen states become more prominent. O(5S) and O(3S) are two states which are identified. XPS studies of the polyethylene surface reacted at high flow rates shows oxygen functionalities that are likely the result of an initiation by hydrogen abstraction. At low flow rates, the products suggest initiation by oxygen insertion. Thus, changes in flow rate can result in major changes to the polymer surface chemistry. © 1996 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 1015-1023 
    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: Bales of antioxidant-stabilized guayule rubber underwent significant losses in bulk viscosity when stored under ambient conditions at an Arizona processing facility. Previous work implicated the unsaturated fatty acid esters present in entrained resin as promoters of such degradation. Aging studies as functions of storage temperature and unsaturated acid ester content were carried out on both bulk rubber and rubber-resin solution (miscella) for cultivar AZ-101. The rate of thermooxidative degradation, determined as a function of Mooney viscosity, was increased by the addition of unsaturated ester. Anaerobic degradation was not affected in this way. The activation energy of chain thermolysis was found to be 116 ± 6 kJ/mol (28 ± 1 kcal/mol). At temperatures above 60°C, chain recombination successfully competed with chain scission in lower viscosity rubber. The rate of thermoox-idative degradation was substantially higher in a typical process miscella. A hindered amine antioxidant significantly reduces chain scission under these conditions. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 23 (1995), S. 573-580 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Factor analysis (FA), the multivariate statistical technique, has been used to extract chemical bonding information from SIMS secondary ion energy distributions. The method is outlined in detail and shown to be capable of constructing quantitative profiles for the chemical states of zirconium present in ZrO2/Zr and ZrNx/Zr structures. In addition, a truncated data collection procedure wherein secondary ion intensity values are collected at a fixed number of emission energy values during the depth profile is outlined. This method, which enables data to be collected in a shorter time and from a smaller sample volume, is subsequently shown to yield reliable results, as confirmed by FA of Auger depth profiles on similar specimens.
    Additional Material: 8 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 26 (1998), S. 188-194 
    ISSN: 0142-2421
    Keywords: SIMS ; secondary ion mass spectrometry ; imaging ; 3D ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Three-dimensional (3D) SIMS images of secondary ion distributions in a solid volume can be produced from a stack of individual images acquired sequentially at different depths during depth profiling of the solid. While it is often possible to obtain visual correlations of large-scale features that occur in several images in the stack, the correlation of less-obvious features requires a more mathematical approach. We present here two cases where image cross-correlation spectroscopy (ICCS) can be used to clarify the presence or absence of organized structure in a 3D depth profile. In one example, the images of deuterium distribution in a zirconium oxide thin film were confirmed to exhibit order over a series of images, thereby suggesting the existence of continuous pores in the material. In a second example, the apparent clustering of gold distributions in a 3D profile of an arsenopyrite mineral was shown to be uncorrelated and likely an artefact of data collection. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 26 (1998), S. 195-203 
    ISSN: 0142-2421
    Keywords: XPS ; x-ray photoelectron spectroscopy ; deconvolution ; resolution ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The maximum entropy method (MEM) is applied to the deconvolution of x-ray photoelectron spectra. This method provides the least-biased estimate of the unbroadened spectrum by using the Shannon information content as the regularizing functional. The large-scale, non-linear optimization problem is solved using a robust variable metric sequential-quadratic programming (SQP) algorithm implemented on a personal computer (PC). The program is tested on simulated spectra and then shown to provide reliable resolution enhancement of measured spectra by unfolding a measured instrumental resolution function. Typical resolution enhancements of 50% are achievable in 〈15 min of computer time. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 7 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 23 (1995), S. 873-878 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A mass-separated low-energy ion beam system was used to deliver pure OH+ and NH+ to 15nm thick polystyrene films on silicon in ultrahigh vacuum. This was done in an effort to produce specific surface chemical functional groups. X-ray photoelectron spectroscopy showed that when the bombardment energy of OH+ exceeded 10 eV, or the dose was higher than 1 × 1016 ions cm-2, a mixture of C—OH, C—C=O and C—COOH groups was produced, along with severe damage to the aromatic rings. However, for bombardment at 10 eV with a dose of 1 × 1016 ions cm-2, only C—OH (or COR) groups were found. Similarly, bombardment with NH+ at 10 eV and a dose 1 × 1016 ions cm-2 induced incorporation of a single nitrogen-containing functionality. The C 1s data indicated that the major chemical functionality on such surfaces in a C—NH2 (or C—NHR) group with a minor component of C—(NH2)2. Hence, surface functionality can indeed be controlled by altering the molecular nature, energy and dose of the bombarding species.
    Additional Material: 7 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 24 (1996), S. 529-530 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: No Abstract
    Additional Material: 2 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 26 (1998), S. 869-871 
    ISSN: 0142-2421
    Keywords: SIMS ; secondary ion mass spectrometry ; EDX ; ore ; Ni, Cu ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: High-resolution SIMS images in conjunction with elastically backscattered electron and energy-dispersive x-ray images have been acquired from a polished slightly oxidized multiphase polycrystalline surface of Ni-Cu sulphide ore. Through correlation of data acquired by the three methods, the extent to which oxidation occurs is shown to be mineral dependent and related to the presence of macroscopic and microscopic surface heterogeneities. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 1 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 23 (1995), S. 163-170 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: This report illustrates, in a stepwise fashion, the application of a new method for quantifying SIMS results (termed the infinite velocity method) to the depth profile analysis of multilayered samples. The two samples analysed comprised a silicon substrate implanted with cobalt and a silicon substrate bearing an oxide layer implanted with boron. Concentrations were extracted by: sampling the secondary ion emissions over several kinetic energies during the depth profile; correcting the resulting intensities for instrument transmission and sputter yield effects, so that these may be poltted against the inverse of the velocity; and referencing the point at which the resulting curves intersect with the intensity axis (intensity at infinite velocity) to an element whose concentration is known, or to the sum of all major element intercept data. Characteristic velocity data obtained from each cycle of the depth profiles were also used to illustrate a new method for defining the position of the interface. To illustrate the validity of these results, peak concentrations were compared with those calculated via the integration method as well as Auger depth profile analysis.
    Additional Material: 7 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 23 (1995), S. 335-341 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Surface properties of Kapton® were analysed after different exposures to ground state fast atomic oxygen (FAO) and vacuum ultraviolet radiation in the atomic oxygen beam facility at the University of Toronto Institute for Aerospace Studies. X-ray photoelectron spectroscopy, scanning electron microscopy and contact angle measurements were used to characterize the chemical and physical changes to the surfaces of the materials analysed. The most important changes in the surface chemistry of Kapton induced by the various exposures to FAO were oxidative degradation of the polymer and substantial changes in supermolecular organization and morphology of the surface layer. A very weak adhesion of the rough top layer to the original Kapton has been observed after an atomic oxygen irradiation with a total fluence of 1.3 × 1021 atoms cm-2, which is comparable to some low earth orbit (LEO) exposures. Comparison was made between pristine samples and the cleaned surface of samples that had been exposed in the atomic oxygen beam facility and in the LEO environment. An ageing effect was observed in the surface layer of exposed samples after a prolonged storage. For several polymer materials, a correlation was found between the erosion yield when exposed to FAO and the dispersion component of the surface tension of the pristine material.
    Additional Material: 5 Ill.
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