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  • 1
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 7300-7304 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The phase diagram of benzene has been investigated up to 550 °C and 30 GPa in a diamond anvil cell by Raman scattering. A new triple point at 400 °C and 5 GPa and a new phase of solid benzene, called phase IV, have been located at high temperature. The boundaries have been determined between the following solid phases: (i) benzene II and benzene III; (ii) benzene III and benzene III'. The irreversible chemical transformation line of benzene has been determined and can be divided in three parts leading to three different recovered compounds. The P–T diagram obtained by our experimental results is discussed in comparison with published works.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 968-974 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Nitromethane has been studied as a model of the energetic nitro compounds. The phase diagram has been determined by Raman scattering in the pressure and temperature ranges of 0–35 GPa and 20–350 °C, respectively. Three new solid phases of nitromethane called III, IV, V, and their domain of stability have been located. A first chemical transformation is observed by the disappearance of nitromethane Raman modes and by the irreversible formation of a transparent solid called compound I (CI). A second chemical transformation [compound I–compound II (CII)], at higher temperature than the first one, is observed by the sudden darkening of the sample. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of chemical reactor engineering 5.2007, 1, A77 
    ISSN: 1542-6580
    Quelle: Berkeley Electronic Press Academic Journals
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The concepts of green chemistry and sustainable development are being considered more and more due to the evolution of regulations and mentalities. In this context, the development of supercritical fluid technologies should go on to evolve in the right direction. Since the nineteen fifties, studies and development efforts have been focused on new ways of separating substances using the specific properties of supercritical fluids. In this context, a mention must be made about the use of carbon dioxide as an extracting agent in many industrial processes (decaffeination of coffee and tea, extraction of hops, spice, aromatic substances, fragrances, pharmaceuticals, etc). Processes using these fluids are particularly attractive at the industrial scale in many fields such as impregnation, analytical and preparative separations, organic synthesis, waste management and material recycling. The industrial development of the supercritical fluid technology is accompanied by numerous research activities, in particular, in the field of inorganic Materials Science for the synthesis of multifunctional nanomaterials.Today, supercritical fluid technology allows the production, with a reduction of the environmental impact, of well designed nanomaterials with controlled properties for applications in many interesting fields, such as catalysis, electronics, energy, optics, pharmacology, etc. This paper is focused on the interest of using supercritical fluids to overcome the drawbacks of solution chemistry approaches for designing multifunctional nanomaterials in term of chemical engineering, sustainable chemistry and control of size, morphology, composition and the structure of nanomaterials.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 7350-7355 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Nitromethane has been studied as a model of energetic alphatic nitro compounds. The initiation of the decomposition mechanism of nitromethane in the vicinity of its explosive decomposition pressure conditions has been studied under high static pressure at ambient temperature by Raman spectroscopy. The vibrational modes νa(NO2) and, to a lesser degree, νs(NO2) show a specific behavior at the solid (II)–solid (III) 7.5 GPa transition (at ambient temperature). A comparison of the Raman spectrum of nitromethane-h3 with new high pressure Raman spectroscopic results for nitromethane-d3 and nitroethane allows one to characterize the physico chemical behavior of these three compounds in relation to their detonic properties. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 379-387 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Polymer [ TiCl2, TiCl3, 3LiCl] complexes were used as solubilized Li/Ti(III) based initiators for Ziegler-Natta polymerization of propene, leading to block copolymers. From measurements of the amount of diblock copolymers produced, a direct determination of the efficiency of the catalytic system was made. This efficiency was found to be equal to about 80% with respect to the number of potentially active centers. The activity of such systems was studied as a function of both initiator concentration and [monomer]0. From the measured values of activity and efficiency of the system, the rate constants of propagation were deduced. The kinetic behaviour of such a system is fully consistent with that of a living one. A first order kinetics towards both propene and active center concentration was found. Therefore, the rate constant of propagation is an absolute rate constant, measuring the intrinsic reactivity of active sites. GPC, 13C NMR and DSC analyses of the block copolymers permitted the establishment of their well-defined linear diblock structure and disclosed a partial stereoregularity of the polypropene block (≈ 50% isotactic triads).
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 675-684 
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Copolymerization of ethylene with propylene (E-P) was initiated with soluble polystyrene \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {100} $\end{document}-butadiene\documentclass{article}\pagestyle{empty}\begin{document}$ \overline 3 $\end{document}-Li/TiCl4 complexes in toluene leading to vinylic-olefinic based block copolymers. The activity of the system was measured at a constant ratio r = Li/Ti for different feed compositions. From measurements of the amount of copolymers produced, a direct determination of the efficiency of the catalytic system was made. This efficiency was found to be close to that obtained for homopolymerizations of C2H4 and C3H6 initiated with the same catalytic complex (≃ 80% with respect to the concentration of “carbon-titanium” bonds).Both the measured values of the efficiency and the determination of the molar masses of the polyolefinic block are consistent with a living character of the system involved in the E-P copolymerization. In such conditions well-defined linear [styrene]-b-[ethylene-co-propylene] copolymers were obtained. Furthermore, 13C NMR analyses allowed determination of the comonomer reactivity ratios, the values of which indicate an E-P random copolymerization.From both these values and those of the absolute rate constants of propagation determined for the homopolymerization of C2H4 and C3H6 initiated with the same catalytic system, the absolute rate constants of cross-propagation were deduced.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 28 (1990), S. 647-654 
    ISSN: 0887-6266
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Copolymerization of ethylene (E) with propylene (P) initiated with soluble (polystyrene)100-butadiene3-Li/TiCl4 complexes leads to [St]-b-[E-co-P] diblock copolymers with a random [E-P] block. GPC and 13C-NMR analyses of copolymers with various compositions and block lengths disclose well-defined linear structures. From DSC measurements of such materials, three different endothermal transition regions are observed: two glass transition regions corresponding, respectively, to the Tg of styrenic and olefinic blocks, and one [E-P] block melting region in which propylene units play a primary role. Furthermore, an additional endotherm is observed, depending on the thermal history of the sample.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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