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  • Polymer and Materials Science  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Ion Impacts and Nanostructures on Ge(111), In0.22Ga0.78As/GaAs(100) and Alpha Quartz Surfaces Observed by Atomic Force Microscopy (1996)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 24 (1996), S. 881-886 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Atomic force microscopy (AFM) is used to compare the topography of the ion-bombarded surfaces of Ge(111), atomically flat terraces on strained layers of In0.22Ga0.78As on GaAs and alpha quartz.Germanium samples were bombarded with 100 keV Ge+ ions at doses of up to 1016 ions cm-2. A cellular structure with a mean pore diameter of 50 nm was observed at greater detail but similar to that reported in earlier scanning electron microscope (SEM) measurements [I. H. Wilson, J. Appl. Phys. 53, 1698-1705 (1982)]. It is proposed that this structure is formed by the intersection of the etched surface with point defect clusters created in the dense collision cascade, and the combined effects of sputter etching, ion reflection and redeposition.Individual impact craters are observed on As+- and B+-bombarded In0.22Ga0.78As/GaAs (35 keV, 1011 ions cm-2) at the areal density identical to that of ion impacts. The craters arising from As+ bombardment are attributed to damage associated with nuclear stopping in the primary collision cascade.By contrast, alpha quartz samples bombarded with a wide range of ions (Pb, Ni, O, Si, Ar and In at doses of 1010-1011 ions cm-2) and energies (30 keV to 0.73 GeV) exhibit asperities (bumps). In the case of very high energy ions, the areal density of asperities is much less than that of ion impacts. The asperities are attributed to volume expansion associated with amorphous zone creation. In the case of very high energy ions, zone creation is attributed to energetic knock-on cascades directed back towards the surface.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Infrared attenuated total reflectance study of latex paint films exposed to aqueous sulfur dioxide (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 38 (1989), S. 173-183 
    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: Fourier-transform infrared/attenuated total reflectance (FTIR-ATR) has been used to investigate the effects of acidic deposition on latex paint films with and without a calcium carbonate extender additive. Paint films approximately 5 mils thick were exposed to aqueous SO2(pH 2.0) for various times by simple immersion. Rapid and complete removal of CaCO3 from the paint film was found to occur, and the kinetics of the removal process were monitored using both weight loss and FTIR-ATR measurements. Both methods revealed Fickian diffusion, with an apparent diffusion coefficient D = 1.84 × 10-9 cm2/s. Good agreement was obtained between D measured via FTIR-ATR and from the weight lost data. The mechanism of removal of CaCO3 from the latex paint films appears to be controlled by the rate at which water and other components of the aqueous SO2 solution can diffuse into the film.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1989.070380116
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  • 3
    Electronic Resource
    Electronic Resource
    Studies of latex paint films exposed to aqueous SO2: pH effects (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 39 (1990), S. 1957-1966 
    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: Latex paint films containing the acid-soluble extender calcium carbonate have been exposed to aqueous SO2 and other acidic solutions to evaluate the effects of acidic deposition at different pH values on the coatings. CaCO3 is completely removed from these films upon immersion in acidic solutions. The leaching process was monitored with weight loss and infrared measurements. The removal rate was found to be strongly dependent on pH, decreasing with increasing pH. Removal of CaCO3 occurs even for distilled water which has been allowed to equilibrate with atmospheric CO2 (pH 5.6). The removal rate seems to depend only on [H+]; the identity of the acidic anion is apparently insignificant. An empirical relation between the rate of removal and pH was formulated from the weight loss data. The analyses of the results from both weight loss and infrared methods suggested that the mechanism of removal at pH 2.0 is diffusion controlled, whereas a chemical reaction involving H+ becomes more important at higher pH values.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070390911
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  • 4
    Electronic Resource
    Electronic Resource
    Studies on the sulfonation of poly(phenylene oxide) (PPO) and permeation behavior of gases and water vapor through sulfonated PPO membranes. III. Sorption behavior of water vapor in PPO and sulfonated PPO membranes (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 52 (1994), S. 29-37 
    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: Water vapor absorption and desorption by poly(phenylene oxide) (PPO) and sulfonated PPO (SPPO) membranes were studied at a constant temperature of 30°C and over a broad range of water activity (0.05 ≤ a 〈 0.8) by the weighing method. The experimental sorption isotherms of both PPO and SPPO possessed a general sigmoidal shape, which suggested that they belong to type II; thus, the data may be quantitatively analyzed according to the BET or GAB equation for multilayer sorption processes. The number of site-bound water molecules per monomeric unit was increased by a factor of 150 after sulfonation of PPO. The features of the reduced absorption and desorption curves of both PPO and SPPO suggested that the sorption processes were non-Fickian. The diffusion coefficient calculated from the slope of the initial linear part of the curves showed concentration dependence. The permeability of water vapor through SPPO was more pressure-dependent than was that through PPO. The Flory-Huggins interaction parameter derived from experimental data on SPPO had a smaller value compared with that of PPO and was a monotonic increasing function of water activity in the low-activity region and then leveled off at a 〉 0.6, showing a corresponding initial decrease of the polymer-water interaction, which then gradually reached a certain stable value. Water clustering for SPPO was much less than that for PPO, which is clear proof of its higher hydrophilicity. The results from this study showed that SPPO could be an excellent dehumidification membrane material. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070520104
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  • 5
    Electronic Resource
    Electronic Resource
    Simultaneous measurement of water diffusion, swelling, and calcium carbonate removal in a latex paint using FTIR-ATR (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 52 (1994), S. 975-983 
    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: An in-situ FTIR-ATR method has been used to monitor the sorption processes of water and pH 1.3-sulfurous acid in two latex paints and the base polymer common to both. The sorption kinetics could not be described by a simple Fickian model. The spectra also showed evidence of polymer swelling, which was confirmed in separate swelling measurements. Anomalous behavior was noted for the latex paint containing CaCO3 when exposed to sulfurous acid. The amount of water sorbed by this sample went through a maximum, then decreased to a constant level. This was accompanied by similar variations in the degree of swelling of the sample. These changes are explained by the rapid loss of CaCO3 from this particular paint upon exposure to acidic solutions, followed by structural rearrangement to fill in the voids left by the CaCO3 particles. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070520716
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  • 6
    Electronic Resource
    Electronic Resource
    Studies on VOCl3/MgCl2/NaY/Al2Et3Cl3 complex support catalysts for the copolymerization of ethylene and propyleneThe work was financed by National Natural Science Foundation of China. (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 54 (1994), S. 1403-1408 
    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: Using VO2+ as a spin probe, a new method to obtain microenvironmental information on supports was developed which can be used in the choice of supports for coordination catalysts. Utilizing the above method, NaY was chosen as second support component. A complex support catalyst VOCl3/MgCl2/NaY/Al2Et3Cl3 was prepared and used in ethylene-propylene copolymerization. Higher polymerization activity was obtained with this catalytic system. Alternating the ratio of two kinds of supports, the composition and sequence structure of copolymers could be controlled, which showed that NaY participated in the active species, affected the insertion of monomer, and changed the composition and sequence structure of copolymers. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070541003
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  • 7
    Electronic Resource
    Electronic Resource
    The absorption of iron by dentin: Its role in discoloration (1996)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 31 (1996), S. 287-292 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study investigated the effect of iron-containing mordants on the discoloration of human dentin. Dentin wafers with intact enamel borders were treated with one of several acid solutions containing iron. After exposure to aqueous sodium sulfide, color change was evaluated colorimetrically. X-ray photoelectron spectroscopy (XPS) and energy dispersive x-ray spectrometry (EDS) were used to probe surfaces for the presence of iron. Changes in surface morphology were evaluated by scanning electron microscopy (SEM). The results indicated that dentin treated by iron-containing solutions always discolored when the sodium-sulfide concentration exceeded 9.7 mM; variability in discoloration occurred below this level. XPS detected iron in enamel but not in dentin, while EDS detected iron in both enamel and dentin. Since XPS probes the upper atomic layers, these results indicate that acid-demineralized dentin absorbs iron; however, a water wash removes iron from the uppermost dentin surface, suggesting that the iron is physically absorbed. When exposed to sodium sulfide, at least some of the iron remaining in the bulk region is able to migrate to the surface to form iron-sulfide compounds. Based on SEM findings, discoloration is associated with the formation of a surface film on dentin. © 1996 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Quantitative AES depth profiling of thin oxide films grown on stainless steels and aluminium (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 19 (1992), S. 60-64 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: AES depth profiling was performed in passive overlayers grown on the surface of stainless steels and in alumina films formed on aluminium at 250°C in oxygen. Our quantitative approach is based on the sequential layer sputtering model proposed by Benninghoven and Hofmann for analysis of thin layers (〈10 nm). A careful measurement of AES sensitivities in pure standards constituted by metallic elements (for the substrate) and their corresponding normal oxides (for the film) is needed to achieve the necessary conversion of AES sputter profiles into atomic concentration profiles. With the assumptions of (1) an oxide film and a metallic substrate assimilated to two distinct media separated by a step-like interface and (2) a time-invariant sputter rate, the method provides an available determination of the film thickness mainly dependent on an appropriate choice for attenuation lengths of Auger electrons. The usual approximations and results should therefore be discussed in the light of the determination of absolute oxygen film contents by means of nuclear reaction analysis (NRA).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740190114
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