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  • Polymer and Materials Science  (910)
  • 1975-1979  (910)
  • 1
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 22 (1978), S. 2217-2228 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The destruction of various UV stabilizers in polypropylene films during irradiation has been examined both in the presence and absence of air and oxidation products. Although some stabilizers were destroyed in the absence of oxygen, all were more sensitive when irradiated in the presence of air. Several stabilizers were highly effective but were destroyed so rapidly that photoprotection of the polymer must have resulted from stabilizer products. Work with preoxidized polymer and with model hydroperoxides and peroxides indicated that most stabilizers were destroyed by the attack of oxygen-centered radicals, with peroxy radical attack appearing to dominate.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A D2-m-dodecacarboranesiloxane containing alternating block copolymer \documentclass{article}\pagestyle{empty}\begin{document}$\rlap{--}[{\rm A}\hbox{---}{\rm B}\rlap{--}]_n$\end{document} was prepared by the reaction of a ureidosilane-terminated polysulfone hard block with a carboranesilanol-terminated carboranesiloxane oligomer. The resulting block copolymer exhibited thermoplastic elastomeric behavior. This unique polymer had excellent thermal stability up to 400°C.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 11 (1977), S. 489-502 
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Physical and in vivo (burned rat model) evaluations as wound coverings were performed for 1) a freeze-dried collagen/poly (∊-caprolactone) (PCL) film laminate, 2) a freeze-dried PCL “foam”/PCL film laminate, and 3) a heat-dried collagen/PCL film laminate. Porcine skin and cadaver skin were also evalulated in vivo for the purpose of comparison. Water-vapor transmission rates and Young's moduli were measured. The degrees of adherence of the coverings to the wound were measured. Grafts which became significantly adherent (〉150 dyne/cm2) to the wound within 1 day were most successful in promoting the formation of a viable tissue bed which appeared ready to accept further grafting. The force required to remove the PCL foam laminate from a full-thickness excision wound was found to increase from 170 dyne/cm2 on the first day postgraft to 1500 dyne/cm2 by the tenth day. The force required to remove freeze-dried collagen laminate remained constant at 200 dyne/cm2 over the 10 day test period. For the heat-dried collagen laminate, a force of only 50 dyne/cm2 was required on day 1, increasing to 200 dyne/cm2 on day 6. Insensible water-loss rates of animals grafted with the laminates were found to be similar to those from animals with human cadaver skin grafts and less than that from animals with porcine skin grafts. When moistened, the laminates prepared using the freeze-dried materials were flexible and somewhat transparent permitting observation of the wound.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 13 (1979), S. 765-782 
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Kinetic and equilibrium studies of blood platelet binding to copolypeptide films show that attachment and serotonin release are not dependent upon the composition of the copolypeptide. Data may be explained by postulating that platelets frequently collide elastically with the surface but leave behind material that modifies subsequent behavior. Similarly, material released from platelets adsorbs at the interface and the extent of attachment and serotonin release are modified and controlled by these adsorbed species. Basically, if the platelet is exposed to a clean surface, its collision with the surface leads to activation and release. In the presence of inert protein, the collision is cushioned by the protein and platelets do not attach or release to any extent. Finally, if protein (or other entities) released from the platelet provide attachment sites, than attachment occurs without release. It is postulated that the behavior of platelets at surfaces is controlled by these interrelated processes.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    ISSN: 0142-2421
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The provision of accurate composition-depth profiles to depths 〉 1 μm is important in the characterization and investigation of thick films, surface coatings, surface treatments and many other technologically important applications. At present, such profiles are usually achieved by sequential ion bombardment and surface analysis and hence involve many difficulties in interpretation due to the non-uniform erosion of surfaces under ion bombardment. In this paper a method of obtaining accurate depth profiles is described using a ball-cratering device. The method employs a rotating ball to fashion a well-defined spherical crater in the sample surface, the depth and width of which can be accurately controlled. The specimen is then cleaned in situ using a scanning ion beam for a short period and the composition-depth profile is obtained either by point-by-point analysis down the sloping sides of the crater wall or by using Auger line-scan techniques across the crater. Coating-substrate interface analysis can also be obtained by sputter-depth profiling at a point on the coating close to the exposed substrate. The method is not only considerably faster than ion etching, but the resulting depth profile also has a well-defined depth resolution. Composition-depth profiles through nitrocarburized mild steel surfaces and protective surface coatings are presented to illustrate the usefulness of the technique.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 15 (1977), S. 973-981 
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Linear D2-m-carborane-siloxanes with one, two, and three trifluoropropyl moieties per repeat unit were prepared by the condensation reaction between bisureidosilanes and carborane disilanol. Molecular weights between 100,000 and 220,000 were obtained. Compared to fluorosilicones, the trifluoropropyl-modified carborane-siloxanes exhibited greater thermal and oxidative stability and in certain cases comparable solvent resistance. The swelling index for carborane-siloxane elastomers decreased with increasing trifluoropropyl content, although this fluorocarbon moiety did compromise the thermal stability of the carborane system.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1411-1418 
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The electroinitiated polymerizations of styrene, 2-vinylnaphthalene, and 9-vinylanthracene were compared in sulfolane and acetone solvents in the presence of ZnCl2. The relative orders of polymerization rates and polymerization efficiencies, in both solvents, were 9-vinylanthracene 〉 2-vinylnaphthalene 〉 styrene, with faster rates and higher efficiencies occurring in sulfolane. Data obtained from viscosity and gel permeation chromatography (GPC) studies indicate that the molecular weights of the polymers produced in these systems are extremely low, 〈5000. Chemical composition and infrared (IR) spectral data suggest that abnormal transfer reactions (possibly from solvent) may be occurring in the electroinitiated 9-vinylanthracene polymerizations. The polymerization mechanism appears to be cationic in these monomer-solvent systems with ZnCl2.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 15 (1977), S. 2673-2684 
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The zinc chloride-catalyzed polymerization of 2-vinylnaphthalene (VN) with both photoinitiation and electronitiation methods was examined. Good yields were obtained with both methods, the electroinitiated process being somewhat faster. The mechanism for polymerization initiation was investigated through a detailed comparison of the kinetics. Both initiation methods show a similar response to increasing input energy and to change in salt to monomer mole ratio. Both methods indicate formation of a ZnCl2-(2-VN)2 complex as intermediate with the formation of the species being rate-determining. These results, together with other similar investigations, are then used to deduce a mechanism that involves the formation of an electronically excited donor-acceptor complex. It is argued that in certain salt-stabilized, electron-delocalized, aromatic systems, such excitation is possible in electroinitiation.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 15 (1977), S. 1563-1571 
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: As part of a program to extend the range of donor-acceptor-initiated polymerization processes, the electroinitiation of 2-vinylnaphthalene in a zinc chloride-sulfolane solution has been studied. Good conversion yields of well-characterized (NMR, IR, GPC, elemental analysis) poly(vinylnaphthalene) were obtained with the process showing several mechanistic similarities to other donor-acceptor salt electropolymerization systems.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 15 (1977), S. 1555-1562 
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The electrochemically initiated polymerization of styrene in methylene chloride solvent with the use of platinum electrodes and tetraalkyl and -aryl group VA halides (i.e., quaternary ammonium, phosphonium, and arsonium compounds) as electrolyte has been investigated. The order of reactivity of the electrolytes with respect to polymerization rate and initiation efficiency was found to be: arsonium 〉 phosphonium 〉 ammonium. Mechanisms involving the electroreduction of the group VA quaternary halides to species capable of electroinitiating polymerization are postulated. The observed losses in solution conductivities during polymerization with the quaternary phosphonium and arsonium electrolytes indicate possible interaction between the initiating radical-ionic species and the supporting electrolyte. In an attempt to further elucidate the mechanism of initiation in these systems, a separate series of experiments, employing the nonpolymerizing monomer, 1,1-diphenylethylene, has been carried out.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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