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  • Articles  (18)
  • Polymer and Materials Science  (16)
  • Geophysics
  • METEOROLOGY AND CLIMATOLOGY
  • Models, Molecular
  • ddc:330
  • 1995-1999  (10)
  • 1975-1979  (8)
  • Physics  (18)
  • 1
    Electronic Resource
    Electronic Resource
    Infrared spectroscopic studies on polyethylene, 5Part 4: cf.1.. The measurement of chain branching on powder polyethylene specimens (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 975-987 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The scope and limitations of the potassium bromide disc technique for the infra-red determination of chain branching in small samples of polyethylene in powder form have been assessed. Many of the samples encountered have an average particle size, prior to grinding with potassium bromide, of about 100 μm and very satisfactory results have been obtained, but the presence of larger particles leads to poor quality discs and inferior results. The well established double beam technique proves suitable for removing the interfering methylene absorption and compensation with polymethylene in the form of a film rather than as a pressed disc is preferable. Difficulties were encountered in preparing branching standards in a uniform and fine powder form, to avoid variation of the absorption coefficient of the 1 378 cm-1 methyl band with particle size. Such powders are best obtained by precipitation from solution rather than by low temperature milling. Despite these problems chain branching measurements may be made with a precision of between 5 and 10% and an accuracy of about 15%.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021800414
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  • 2
    Electronic Resource
    Electronic Resource
    Infrared spectroscopic studies on polyethylene, 1. The measurement of low levels of chain branching (1976)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 437-448 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Probleme, die bei Anwendung der Kompensationsmethode auf IR-spektroskopische Bestimmungen von niedrigen Verzweigungsgraden in Polyäthylenen hoher Dichte auftreten, werden systematisch untersucht. Die erzielbare Genauigkeit wird bestimmt und es wird gezeigt, daß, wenn möglich, eine Korrektur für die Methyl-Endgruppen angewendet werden sollte. Diese ist bei einigen Polymertypen leicht möglich, bei anderen hingegen schwieriger. Als Kompensationskeil im Referenzstrahl des Spektrometers verwendet man besser Polymethylen als hochmolekulares Polyäthylen. Die äußerste Empfindlichkeit, die mit der manuellen Kompensationsmethode erreicht werden kann, liegt bei einem Methylzweig pro 2000 C-Atome. Wenn diese Methode jedoch ergänzt wird durch Computer-Kurvendämpfung und Computer Mittelung über zahlreiche Momentspektren (“C.A.T.”), kann noch eine deutliche Verbesserung im Signal-Rausch-Verhältnis erzielt werden. Damit wird es möglich noch Verzweigungsgrade bis herunter zu 0,1 Methylgruppen pro 1000 C-Atome zu messen.
    Notes: The problems encountered in the infrared spectroscopic estimation of the low levels of chain branching present in high density polyethylene, using the compensation method, are discussed systematically. The precision to be expected has been determined and it is shown that, if possible, a correction should be applied for methyl groups present at the chain ends. This is feasible with some types of polymer but more difficult with others. The compensating wedge in the reference beam of the spectrometer should be made of polymethylene rather than a high molecular weight polyethylene. The ultimate sensitivity of the manual compensation method is about one methyl branch per two thousand carbon atoms. However, when this is supplemented by computer smoothing and off-line computation of average transients (C.A.T.), a significant improvement is obtained in the signal to noise ratio, and branching levels down to 0,1 methyl groups per thousand carbon atoms are readily measured.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1976.021770212
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  • 3
    Electronic Resource
    Electronic Resource
    Use of auger and x-ray photoelectron spectroscopy to study the locus of failure of structural adhesive joints (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 2375-2392 
    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 techniques of Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) have been used to study the locus of failure of epoxy resin joints. The effects of a long water immersion and the application of a silane-based primer have also been studied. Results indicated that for dry joints fracture occurred near an epoxy resin/metal interface while with water-soaked unprimed joints, fracture occurred interfacially between the adhesive and iron oxide. The application of the primer to the metal surface prior to bonding prevented the formation of a water-formed oxide although fracture was then found to occur through the primer.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210907
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  • 4
    Electronic Resource
    Electronic Resource
    Computer optimization of reverse osmosis processing of soy whey with cellulose acetate modules (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 749-762 
    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: In processing full-fat soy flour to an acid-precipitated lipid protein concentrate a byproduct whey fraction results which, because of its high biological oxygen demand, represents a serious disposal problem. Processing of food waste streams by reverse osmosis has received considerable attention because of its low theoretical energy requirement since no phase change is involved. In a previous study at this Center a mathematical model was developed for the diffusive transport of soy lipid protein concentrate whey across cellulose acetate membranes. In this study, pumping energy and power costs combined with membrane life and replacement costs were incorporated into the original model to provide a basis for optimization from an energy cost standpoint. Computer-simulated runs were compared with experimental pilot-plant runs, and the agreement between predicted and actual results was quite good. Water flux rates were in the range of 3 to 7 gal/ft2/day. Computer runs were used to optimize the processing of 100,000 gal/day of soy whey at 8000 ppm biological oxygen demand (BOD). Costs were at a minimum with a six-stage tapered flow primary reverse osmosis treatment over a porous cellulose acetate membrane, followed by a six-stage tapered flow reverse osmosis over a tighter membrane. BOD reduction was 94% at a cost of $5.45/1000 gal.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070240312
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  • 5
    Electronic Resource
    Electronic Resource
    Cross-linking of poly[1-(trimethylsilyl)-1-propyne] membranes using bis(aryl azides) (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 959-968 
    Details
    ISSN: 0887-6266
    Keywords: PTMSP ; cross-linking ; membranes ; permeability ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Cross-linkable poly[1-(trimethylsilyl)-1-propyne] (PTMSP) films were cast from toluene solutions containing PTMSP and either 4,4′-diazidobenzophenone or 4,4′-(hexafluoroisopropylidene)diphenyl azide. The composite films were clear and homogeneous and were cross-linked by UV irradiation at room temperature or thermal annealing at 180°C. Low levels of the bis(aryl azide) (1-5 wt %) were effective in rendering the films insoluble in toluene and THF, both good solvents for PTMSP. The process is simple and effective, and thus PTMSP can be readily converted to mechanically stable membranes with permeabilities and separation factors comparable or higher than those of poly(dimethylsiloxane). The films were characterized by measuring their density, their permeability toward O2 and N2, and their spectroscopic properties. Compared to PTMSP, films containing bis(aryl azide) cross-linkers had lower permeabilities and higher separation factors, consistent with a reduction in free volume. When the films were cross-linked photochemically, the permeabilities declined further and the separation factor increased. Films cross-linked thermally had permeabilities comparable to their PTMSP/azide precursors, and density and swelling measurements suggest that higher free volumes are obtained in thermally cross-linked films. All films stored in air suffered from a slow decline in permeability which may reflect slow surface oxidation of the films. When stored in vacuum, cross-linked films were stable and showed no loss in permeability, but the permeability of uncross-linked PTMSP films stored under the same conditions fell to 70% of their original value in 1 month. We attribute the permeability decline to densification accelerated by impurities and solvents. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 959-968, 1998
    Additional Material: 5 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Hysteresis in the glucose permeability versus pH characteristic for a responsive hydrogel membrane (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 17 (1996), S. 409-415 
    Details
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A side-by-side diffusion cell was used to study the permeability of glucose through a temperature- and pH-sensitive poly(N-isopropylacrylamide-co-methacrylic acid) hydrogel membrane. At fixed temperature (37°C), lowering pH in one side of the cell induced hydrogel volume collapse and strongly attenuated glucose permeation across the membrane. Hysteresis was observed in the glucose permeability versus pH characteristic.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1996.030170607
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  • 7
    Electronic Resource
    Electronic Resource
    Polymer encapsulation of arsenic-containing waste (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 2039-2046 
    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 potential for encapsulation of arsenic waste by combination with two commodity polymers was evaluated. Initial studies employed nontoxic substitutes, these being gypsum and calcium carbonate, with host polymers being predominately a recycled grade of polyethylene (PE) and a synthetic elastomer. The latter was used at low processing temperatures with rather volatile arsenic compounds. The gypsum caused processing difficulties due to evolved water, but the CaCO3 was able to be readily combined at high volumes. Arsenic trioxide was able to be incorporated at modest levels in PE and was less successfully combined with the rubber. However, the higher processing temperatures needed for PE caused the As2O3 to sublime. Less volatile calcium arsenite, readily prepared from As2O3, was able to be mixed at high volume ratios with the rubber, although processing with PE was less successful. These results may be used in conjunction with other methods for stabilization and would be applicable to other forms of medium- to high-level waste. © 1995 John Wiley & Sons, Inc.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070581115
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  • 8
    Electronic Resource
    Electronic Resource
    Observations on the thermoreversible gelation of two-directional arborols in water-methanol mixtures (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 2787-2793 
    Details
    ISSN: 0887-6266
    Keywords: gel ; arborol ; dendrimer ; freeze-fracture electron microscopy ; small-angle X-ray scattering ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reversible gels of two-directional cascade polymers with hydrophilic groups covalently attached by an hydrophobic center chain were studied by light and small-angle X-ray scattering, differential scanning calorimetry, and freeze-fracture transmission electron microscopy. The long, self-assembled fibers interact side-by-side over extended regions to form bundles. A given fiber may participate in several bundles, thus forming a three-dimensional gel network. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2787-2793, 1997
    Additional Material: 8 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    The synthesis and properties of a cation-exchange resin prepared by the pyrolysis of starch in the presence of phytic acidNames are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable. (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 57 (1995), S. 385-390 
    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: A black charcoal-like material having cation exchange and adsorption properties was prepared by the controlled pyrolysis of starch in the presence of a commercial phytic acid solution. Resins with binding capacities of 0.7-5.7 meq/g of calcium were prepared by varying the phytic acid to starch ratio, the temperature, or the duration of heating of the reaction mixture. SEM photomicrographs of some of these new materials showed that they are composed of particles similar in size and shape to the starting starch granules. These resins also removed atrazine from aqueous solutions. © 1995 John Wiley & Sons, Inc.This article is a US Government work and , as such, is in the public domain in the United States of America.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070570315
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  • 10
    Electronic Resource
    Electronic Resource
    Syndiotactic polystyrene preparation in a rim process (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 62 (1996), S. 1807-1818 
    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: Very few polymeric systems are suitable for preparing engineering parts using reaction injection molding (RIM) processing. A new two-component metallocene catalyst, which is able to polymerize bulk styrene at high rates to the syndiotactic form, was studied. The catalyst used in this work was based on monocyclopentadienyl analogs of titanium (Cp*TiMe3), which was used in conjunction with a boron cocatalyst [B(C6F5)3]. When separate streams of the catalyst and cocatalyst, dissolved in either styrone or styrene/toluene solutions, met in a mixhead, the styrene polymerized rapidly to form crystalline, syndiotactic polystyrene (s-PS). Using a bench scale RIM device, the monomer conversion during polymerization was monitored through the quasi-adiabatic temperature rise, recorded by a rapid data acquisition system. The rate equation was found to be second order with respect to the monomer concentration and first order with respect to the catalyst concentration, given some assumptions. The s-PS was brittle and attempts were made to incorporate elastomer toughening into the reacting system. Several potential problems associated with using this system for RIM process discussed. © 1996 John Wiley & Sons, Inc.
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