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  • Polymer and Materials Science  (309)
  • 1990-1994  (309)
  • 1980-1984
  • 1993  (309)
  • 1
    Electronic Resource
    Electronic Resource
    Metal ion concentrations in retrieved polyethylene total hip inserts and implications for artifactually high readings in tissue (1993)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 27 (1993), S. 1349-1355 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Although there are many studies which document high metal ion concentrations in clinically retrieved tissues surrounding total joint replacements, most investigations have remained cautious in their interpretation due to the artifactual influences of metal particulate.The possible contribution of polyethylene wear debris to artifactually high periprosthetic metal ion concentration readings has not been previously considered. This study documents the potential role of polyethylene particulate contamination in causing artifactually high metal concentration readings in tissues.The data showed metal ion contamination in the polyethylene was progressive at each stage of exposure to metal: from bar stock preparation, to manufacturing, to in vivo ambulation. The manufacturing and machining processes showed a statistically significant (P ≤ .05) increase in metal ion concentrations in the nonarticulated acetabular inserts over bar stock.The results of this study demonstrate that periprosthetic tissue and synovial fluid metal ion concentration data must be interpreted with caution due to possible artifactual problems associated with metal ion contaminated polyethylene particulate. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820271102
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  • 2
    Electronic Resource
    Electronic Resource
    Gamma-, photo-, and thermally-initiated oxidation of isotactic polypropyleneIssued as NRCC #34241. (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 715-722 
    Details
    ISSN: 0887-624X
    Keywords: polypropylene ; oxidation products ; gamma ; photoinitiation ; thermal ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The detailed oxidation products have been identified and compared from the γ-, photo-, and thermally-initiated oxidation of unstabilized polypropylene films. Products were identified and quantified by a combination of iodometric analysis and infrared spectroscopy. Spectral resolution was enhanced by derivatization reactions which allow the quantification of primary, secondary, and tertiary hydroperoxide and alcohol groups as well as more reliable analysis of carbonyl species. In contrast to polyethylene oxidation which yields predominantly ketone with lesser amounts of secondary hydroperoxide and carboxylic acid, polypropylene oxidizes to give predominantly tertiary hydroperoxide and lesser quantities of secondary hydroperoxide and ketone. In addition carboxylic acid groups are a minor product except at high degrees of thermal and photoinitiated oxidation. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080310316
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  • 3
    Electronic Resource
    Electronic Resource
    Investigation of the free radical polymerization of styrene in the presence of several 1,1-disubstituted ethylenes (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 901-908 
    Details
    ISSN: 0887-624X
    Keywords: styrene ; free radical ; addition-fragmentation chain transfer ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A variety of 1,1-disubstituted ethylenes, having an electron-withdrawing (capto) and an electron-donor (dative) substituent on the same carbon, were synthesized and added to styrene polymerizations. The dative substituents investigated were alkoxy or alkylcarbonate. After the addition of a polystyryl radical to a disubstituted ethylene, the resulting alkoxy or carbonate radicals could potentially fragment, resulting in chain termination and the formation of alkyl radicals. This process is called addition-fragmentation chain transfer (AFCT). The polymers produced during this study were examined for evidence of copolymerization and AFCT. The relative stability of the radicals generated by the fragmentation process appears to be the predominant factor controlling the ratio of copolymerization versus AFCT. © 1993 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080310408
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  • 4
    Electronic Resource
    Electronic Resource
    PVD-beschichtete Tribosysteme bei reversierender Gleitbeanspruchung (1993)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 24 (1993), S. 160-167 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: PVD-coated tribosystems at reciprocating slidingThe aim of the investigation is to increase the life time of machinery elements of steel, sliding under high contact pressure, by PVD-coating of one of the surfaces.The three-step tribological testprogram includes a fundamental test, a model test under real conditions and a suitability test with real parts. The coefficient of friction and wear depends on substrate material, deposition variance, coating structure and surrounding conditions.Hard coatings: They enlarge the life time of lubricated systems considerably (μ ≤ 0,1). Without lubrication the coefficient of friction is relatively high (μ ≥ 0,5), which results in a short life time.Coatings with low friction: Soft metals and chalchogenides on supporting hard coatings only reduce the friction for a short time. Metal carbon coatings yield the lowest coefficient of friction (μ = 0.2) and the greatest life time. In the range up to 1500 N/mm2 the pressure has a small influence on the life time. When the coated contact surface slides against an unmachined forged surface, the coating will be damaged after a short time due to local over oad at asperities.
    Notes: Das Ziel der Untersuchungen ist die Steigerung dcr Lebensdauer von unter relativ großen Pressungen gleitend beanspruchten Maschinenelementen aus Stahl durch PVD-Beschichtung eines der Kontaktpartner. Die tribologische Prüfung erfolgt dreistufig durch grundlagennahe Modellprüfung, beanspruchungsähnliche Modellversuche und Versuche am Bauteil (Steckkette) unter Praxisbedingungen. Substratwerkstoffe, Schichtsystem und Umgebungsbedingungen beeinflussen das Reibungs- und Verschleißverhalten wesentlich.Hartstoffschichten: Im geschmierten System verlängern sie die Lebensdauer erheblich (μ ≤ 0,1). Ohne Schmierung ist die Reibungszahl relativ groß (μ ≥ 0,5), was zum frühzeitigen Versagen des Tribosystems führt.Reibungsmindernde Schichten: Weichmetalle und Chalkogenide auf hartstoffbeschichteten Systemen vermindern die trockene Reibung nur kurzzeitig. Die kleinste Reibungszahl (μ = 0,2) und die größte Lebensdauer erbringen die Metall-Kohlenstoff-Schich-ten. Im Bereich bis zu 1500 N/mm2 hat die Pressung nur einen kleinen Einfluß auf die Lebensdauer. Bei Reibung gegen unbearbeitete, geschmiedete Steckkettenelemente wird die Schicht infolge lokaler Überbeanspruchung an Punktkontakten frühzeitig geschädigt.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19930240315
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  • 5
    Electronic Resource
    Electronic Resource
    Grundlegende Betrachtungen zur Eigenspannungsanalyse an Keramik-Metall-Verbunden mittels FEM (1993)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 24 (1993), S. 20-25 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Fundamental Investigations of Residual Stresses in Metal-Ceramic-Joints by FEMThe reduction of damages in metal-ceramic-joints caused by residual stresses is of essential significance. Therefore, a model was created to simulate the behaviour of metal-ceramic-joints under thermal stress. In this paper, results of fundamental investigations are presented.
    Notes: Eigenspannungen in Metall-Keramik-Verbunden führen häufig zu deren vorzeitigem Versagen. Im vorliegenden Beitrag werden Ergebnisse aus Grundlagenuntersuchungen vorgestellt, bei denen der Einfluß wesentlicher Werkstoffkennwerte untersucht sowie ein Vergleich der Rechenergebnisse mit Laboruntersuchungen vorgenommen wurde.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19930240115
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of thermal treatment on heating characteristics of Ni—Cu alloy for hyperthermia: Preliminary studies (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 4 (1993), S. 55-60 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Ferromagnetic Ni—Cu alloy wires were characterized in order to obtain well-defined thermoseeds for application in interstitial hyperthermia of prostate cancer. Thermoseeds have been produced which possess Curie points in the therapeutic hyperthermia range, approximately 40 to 50 °C. The effect of thermal treatment and composition on the heating characteristics of the thermoseeds were investigated. The preliminary study shows that the recrystallization is crucial for altering thermoseeds' heating characteristics. Obtaining thermoseeds which behave as desired depends on changes in annealing times and temperatures. One may increase the maximum heating temperature (similar to Curie temperature) by increasing the annealing time and cooling time. Decreasing the lower annealing plateau temperature also increases the maximum seed heating temperature. Higher nickel content compositions did not affect rise time but increased the maximum heating temperature. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770040107
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  • 7
    Electronic Resource
    Electronic Resource
    Laser-induced deposition of aluminium on gallium arsenide from trimethylamine alane (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 2 (1993), S. 53-61 
    Details
    ISSN: 1057-9257
    Keywords: Laser chemical vapour deposition ; Al deposition ; Photolysis ; Pyrolysis ; Trimethylamine alane ; Laser direct writing ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Aluminium microstructures (dots or strips) have been photodeposited on GaAs substrates via the decomposition of a solid precursor, the 2:1 hydride adduct of Al, called trimethylamine alane (TMAA).The dissociation of TMAA, the vapour pressure of which can be varied between 0.4 and 1 mbar by dilution in hydrogen carrier gas, has been achieved via a pyrolytic process using a CW Ar+ laser operating in the visible range (488-514 nm). This decomposition reaction occurs at laser powers higher than 0.3 W, i.e. at laser-induced temperatures higher than 130°C, and leads to the formation of high-purity aluminium strips as observed from Auger electron spectroscopy (AES) and energy-dispersive X-ray analysis (EDX) data. The deposition rates are in the range 50-1400 Å s-1. The minimum of line resistivity measured versus scanning speed and laser power is 6.5 μΩ cm.The photolytic decomposition of TMAA has been performed at room temperature within the laser spot area using a CW UV laser (intracavity frequency doubler emitting at 257 nm). The formation of aluminium clusters has been observed at very low deposition rates (20 Å s-1). However, these tiny clusters react quickly with oxygen and are transformed into alumina clusters.All these results have been tentatively explained on the basis of the surface reactivity of H2 and TMAA regarding GaAs or Al, as obtained by other workers through surface science techniques and mass spectrometry.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860020107
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  • 8
    Electronic Resource
    Electronic Resource
    Visible fluorescence on IR excitation of polar dimethylaminobenzylidene 1,3-indandione crystals (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 2 (1993), S. 221-232 
    Details
    ISSN: 1057-9257
    Keywords: Dimethylaminobenzylidene ; 1,3-indandione crystals ; Non-linear optical effects ; Electronic structure ; Absorption and luminescence spectra ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: A novel non-linear fluorescence (NLF) effect in polar dimethylaminobenzylidene 1,3-indandione (DMABI) crystals is presented and discussed. A single crystal or vacuum-evaporated layer of DMABI excited in the IR region at 1064 nm (by a Q-switched YAG laser) emits red light in the visible region of the spectrum at 600-740 nm depending on the DMABI crystalline modification. This anti-Stokes luminescence shows a quadratic dependence on the exciting light intensity which transforms to a linear dependence at very high excitation intensities. The observed NLF effect under IR excitation is determined by optical transitions into intermolecular charge transfer (CT) states. It has been suggested that the photoexcited singlet 1CT excitations may either interact in a quadratic singlet-singlet (1CT + 1CT) annihilation reaction or, more probably, form long-lived triplet 3CT excitons via a hyperfine interaction effect which may subsequently annihilate in a similar bimolecular fusion reaction (3CT + 3CT). In both cases the excited molecular singlet state S1 is formed and thus the NLF effect is due to singlet-singlet or triplet-triplet fusion of CT excitons. A detailed energy diagram and kinetic description of the model are presented. Quantum chemical calculations of the electronic structure of the DMABI molecule illustrate the dipolar nature of its ground and excited states.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860020503
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  • 9
    Electronic Resource
    Electronic Resource
    Investigation of the formation of physical damage on automotive finishes due to acidic reagent exposure (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 50 (1993), S. 541-549 
    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: Automotive paints with clear-coat surfaces can be physically damaged by exposure to acidic reagents produced in a smog chamber designed to reproduce real environmental conditions. Visual and reflectance microscopy observations show that deposition of material formed from the reaction of the clear coat and the reagent drop occurs on the paint surface after the drop evaporates to a critical size, with the greatest deposition occurring at the edge of the drop. This type of deposition suggests a free-energy minimization process favoring the formation of stable nuclei at the reagent drop edge. With heating after the drop evaporation to simulate exposure to the sun, a damaged area containing sulfur that is in the shape of a circular ring is observed at the location of the deposits. The majority of the visual damage appears to result from an interaction between the deposit and the paint at elevated temperatures. Results from profilometry, scanning electron microscopy, and reflectance microscopy show that the damaged areas are ring-shaped cracked blisters on the surface resulting from the clear coat separating into layers. © 1993 John Wiley & Sons, Inc.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070500317
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  • 10
    Electronic Resource
    Electronic Resource
    Study on the synthesis of perfluorovinyl-sulfonic functional monomer and its copolymerization with tetrafluoroethylene (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 47 (1993), S. 735-741 
    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: Tetrafiuoroethylene (TFE) and hexafluoropropylene (HFP) were subjected to reactions with freshly distilled sulfur trioxide to obtain 1-fluorosulfonyldifluoro-acetylfluoride (FSDFAF, yield 65-70%) and pentafluoro-2-propenylfluorosulfate (PPFS, yield up to 50%). A subsequent reaction of FSDFAF with PPFS under anhydrous conditions led to a preparation of 2-(1-pentafluoro-2-propenyloxy)tetrafluoroethanesulfonyl fluoride (PPOTESF, yield 40-41%) whose structure was proved by both infrared (IR) spectroscopy and nuclear magnetic resonance (19F NMR). TFE was copolymerized with PPOTESF in bulk by using a free radical initiator of the hydrocarbon type at a temperature of 50°C. Various TFE/PPOTESF mole ratios were employed and the presence of sulfonyl fluoride (—SO2F) functional groups in the copolymers was proven by IR spectroscopy. The copolymers were subjected to alkaline hydrolysis and the —SO2F content was found not to exceed 0.70-0.80 mEq/g with polymer yields in the range of 11-31%. The reactivity ratios r1 and r2 related to TFE and PPOTESF, respectively, were determined by using the Fineman-Ross method. A random distribution of PPOTESF units along the polymeric chain, consisting mainly of TFE fragments, was found to exist. The copolymers had melting temperatures 40-45°C lower than polytetrafluoroethylene and were thermally stable to 305-315°C. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070470417
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