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  • Polymer and Materials Science  (239)
  • EARTH RESOURCES AND REMOTE SENSING  (140)
  • 1980-1984  (379)
  • 1982  (379)
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Keywords
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  • 1980-1984  (379)
Year
  • 11
    Electronic Resource
    Electronic Resource
    Surface oxidation of cis-trans polybutadiene (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 1269-1276 
    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: Uncrosslinked cis-trans polybutadiene films were prepared on ultraclean glass microscope slides by uniform dipping. The samples were stored in different environments prior to evaluation of surface oxidation by dynamic contact angle using the Wilhelmy plate method and by X-ray photoelectron spectroscopy (XPS). Storage conditions evaluated were: (1) laboratory air at 20°C and 30% relative humidity; (2) vacuum at 0.1 torr; (3) distilled water equilibrated with air; and (4) degassed distilled water. XPS and contact angle analysis indicate that samples exposed to air undergo significant surface oxidation within 8 h. Exposure of polybutadiene to air-equilibrated water results in slower oxidation. Samples stored in degassed water demonstrated less surface oxidation. Vacuum-stored samples demonstrated the least surface oxidation. Dynamic contact angle measurements demonstrated that receding contact angles are more sensitive to changes in surface oxidation than are advancing contact angles, as expected. Changes in surface wetting characteristics are readily observed after only 1 h in laboratory air, although XPS analysis does not show evidence of oxidation within 4 h of air storage.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1982.070270416
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  • 12
    Electronic Resource
    Electronic Resource
    Kinetics of polymerization of styrene. The catalyst system Cu2Cl2 + AlEt3 in n-hexane (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 4861-4866 
    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: Studies on polymerization of styrene by the heterogeneous catalyst system Cu2Cl2 + AlEt3 are reported. Kinetic studies carried out at an optimum catalyst composition [Al]/[Cu] = 0.8 and aging time of 4 h give a value of 55 kJ/mol for the activation energy. The rate law can be presented as R = K [cat] [mon]2. A radical mechanism is proposed on the basis of the effect of hydroquinone and ESR spectra. The mechanism of polymerization with this catalyst system is different than that of CuCl2 + AlEt2X (X = Br, Cl), which was reported earlier.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1982.070271230
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  • 13
    Electronic Resource
    Electronic Resource
    Modifizierte ozonolyse zur bestimmung von internen doppelbindungen in polyvinylchlorid (1982)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 104 (1982), S. 145-161 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The determination of internal double bonds in PVC by oxidative chain scission with ozone in tetrachloroethane (TCE)-solution at -20°C can be quickly and easily performed measuring directly the intrinsic viscosities of samples during the reaction. Using a series of PVC-standards, the evaluation of the Mark-Houwink constants for TCE as solvent resulted in K = 0.027 [cm3/g] and α = 0.75. 1H-NMR-spectroscopic studies of the ozonolysis of model compounds as oleic acid and low molecular PVC fractions provided some information on the mechanism of the ozonolytic scission under the applied reaction conditions.
    Notes: Die Bestimmung der internen Doppelbindungen in PVC ist durch oxidative Spaltung mit Ozon in Tetrachlorethan (TCE)-Lösung bei - 20°C schnell und einfach möglich, indem die Grenzviskositäten der vor und während der Ozonolyse entnommenen Proben direkt im Reaktionsmedium ermittelt werden. Die zur Berechnung der Molekulargewichte benötigten und mit einer Reihe von PVC-Eichsubstanzen für TCE ermittelten Konstanten der Viskositäts-Molekulargewichts-Beziehung sind K = 0,027 [cm3/g] und α = 0,75. Durch 1H-NMR-spektroskopische Untersuchung von Modellverbindungen wie Ölsäure und niedermolekularen Anteilen aus PVC konnte ein Einblick in den Mechanismus der ozonolytischen Spaltung unter den ausgearbeiteten Reaktionsbedingungen erhalten werden.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1982.051040113
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  • 14
    Electronic Resource
    Electronic Resource
    Irradiation crosslinking of the polytetrapeptide of elastin and compounding to dacron to produce a potential prosthetic material with elasticity and strength (1982)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 16 (1982), S. 11-16 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The poly(tetra peptide), H- (L·Val1-L·Pro2-Gly3-Gly4)n-L·Val-OMe, which is a recurring sequence in tropoelastin the precursor protein of the elastic fiber, has been irradiation crosslinked to produce an elastomeric material with limited strength. When a material such as a Dacron fabric is impregnated by the coacervate phase of the poly(tetra peptide) prior to irradiation crosslinking at 50 Mrad, the crosslinked product exhibits stress-strain curves with good elastomeric properties and high strength. In addition to the stress-strain curves, the material is characterized by scanning electron microscopy.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820160104
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  • 15
    Electronic Resource
    Electronic Resource
    Effect of pore size on the peel strength of attachment of fibrous tissue to porous-surfaced implants (1982)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 16 (1982), S. 571-584 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Twenty-four rectangular metal plates were fabricated with surface regions in three different pore size ranges (5-20 μm, 20-50 μm, 50-200 μm). The plates were implanted into the dorsal subcutaneous tissue of 12 adult mongrel dogs for periods of 4, 8, 12, and 16 weeks. After animal sacrifice, the fibrous tissue which adhered to the porous-surfaced regions of each plate was mechanically peeled off to give an indication of the strength of tissue attachment. The tissue was examined by both transmitted light and scanning electron microscopy. At each time period, the tissue that contacted the porous regions was found to be collagenized fibroconnective tissue. The mechanical tests indicated an increasing strength of tissue attachment with increasing implantation time and pore size range. The largest pore size range of approximately 50-200 μm produced a mean peel strength of attachment of 27.5 g/mm at the 16-week period.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820160505
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  • 16
    Electronic Resource
    Electronic Resource
    Enzymatic removal of formalin-fixed tissues from polyester arteries, and its effect on physical properties of fibersAn oral presentationof the resultts of this article was made before the Medical Plastics Division of the Society of Plastic Engineers, 39th Annual Technical Conference, Boston, MA, May 4, 1981. (1982)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 16 (1982), S. 659-668 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A method is presented that can be utilized for the removal of formalin-fixed tissues from arterial grafts without. Affecting fiber material properties. Such a method could prove highly useful for studying the changes in the structure and properties of graft fiber as functions of important clinical variables. Information on what actually happens to the arterial graft material in situ with passage of time is greatly lacking in the current graft literature. The method proposed involves treatment of the formalin fixed fiber-tissue complex with an enzymatic preparation containing enzymes derived from the porcine pancreas (pancreatin) in solution with tris(hydroxymethyl) aminomethane buffer at pH 7.6. Studies with two different grafts - a Microknit Dacron Bifurcation from a clinical patient 10¼ years after implantation and stored in formalin for 11 months, and a Sauvage Filamentous Velour of Dacron from an animal 24 h after implantation and stored in formalin for nine months - showed that the treatment was highly effective in completely removing the tissues at concentrations of pancreatin as low as 2.5%. The same treatment given to the virgin yarns of grafts revealed no significant effects on tensile, dimensional, and morphological properties.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820160513
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  • 17
    Electronic Resource
    Electronic Resource
    A comparison of the in vitro cytotoxicity of four restorative materials assessed by changes in enzyme levels in two cell types (1982)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 16 (1982), S. 519-528 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A system is described for assessing the toxicity of freshly mixed restorative materials in vitro by measuring changes in the levels of β-galactosidase and lactic dehydrogenase in both cultured cells and supernatants. The toxic effects of a zinc phosphate and silicate cement, a composite, and zinc oxide/eugenol were studied on two cell types, macrophages and fibroblasts, after 24 h exposure. Zinc oxide/eugenol, Silicap, and zinc phosphate were toxic to macrophages, in that order; Concise appeared to be nontoxic. Only zinc oxide/eugenol exerted significant effects on fibroblasts. Interposing dentine powder between the test cells and the material ameliorated the effects of all materials, possibly by the absorption of toxic components.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820160417
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  • 18
    Electronic Resource
    Electronic Resource
    Reaction of mercury with silver-tin dental amalgam alloy (1982)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 16 (1982), S. 535-547 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Electron diffraction evidence confirming the ordered orthorhombic crystal structure of the γ phase of the silver-tin system has been obtained, and it has been established by optical metallography that an alloy with a composition corresponding to the dental amalgam alloy formula Ag3Sn (i.e., 26.85 wt % Sn) lies outside the single γ phase field and in the duplex (γ + Sn) phase field adjacent to it. Studies of the mechanism of the hardening reaction of single crystals of homogeneous γ phase alloys with mercury were carried out using both scanning and transmission electron microscopy. Mercury attack occurred preferentially along welldefined planes in the single crystals. Using electron channeling and trace analysis techniques these planes of preferential attack were found to be {010} and {011}, and from transmission electron microscopy of thin foils these were shown to be slip bands and deformation twins, respectively. In bicrystals of γ phase material, preferential attack also occurred along grain boundaries. Similar preferential mercury attack, leading to the development of deep planar intrusions into the γ phase material, was observed in an experimental dental amalgam prepared from a lathe-cut homogeneous γ phase amalgam alloy. It is believed that the presence of such features would have important implications for the clinical performance of dental amalgam.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820160502
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  • 19
    Electronic Resource
    Electronic Resource
    Decomposition of polypropylene hydroperoxide by hindered aminesIssued as NRCC No. 19889. (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 20 (1982), S. 575-582 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hindered amine-induced decomposition of polypropylene hydroperoxide was studied in the solid state and in the presence of a liquid solvent and the polymer was compared with model hydroperoxides. The high reactivity of the macrohydroperoxides appears to be related to the adjacent, hydrogen-bonded hydroperoxide groups that occur in the polymer. The hindered amines are converted to nitroxides in the reaction via hydroxylamine intermediates. Amine-induced decomposition of polypropylene hydroperoxide is faster in the absence of a liquid solvent for the amine than in the presence of the solvent, probably because of the strong amine-hydroperoxide association that occurs in the solid state. The decomposition process in the solid state is sufficiently rapid for the reaction to contribute to the effectiveness of hindered amines in the light stabilization of polymers.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.170200231
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  • 20
    Electronic Resource
    Electronic Resource
    Spectroscopic study of rigid-rod polymers. II. Protonation effect (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 509-521 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The protonation of a heterocyclic rigid-rod polymer poly(p-phenylene benzbisthiazole) and its model compound has been studied by UV-visible and Raman spectroscopy. Because of the two nitrogens on the heterocyclic ring, spectroscopic features of unprotonated, half-protonated, and fully protonated structures have been identified. For the fully protonated molecule, there is also an increase in conjugation between the phenyl ring and the heterocyclic ring.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.180200312
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