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  • 1
    Electronic Resource
    Electronic Resource
    Investigation of axial density modulations of core fibrils by interface distribution functions (1986)
    Springer
    Colloid & polymer science 264 (1986), S. 1017-1023 
    Details
    ISSN: 1435-1536
    Keywords: Core-fibrils ; axial density — modulation ; interface distribution functions ; defect clustering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The axial density modulation of core-fibrils in polypropylene and poly (1butene) crystallized from the oriented melt has been investigated by calculating interface distribution functions of the small angle x-ray scattering. The density modulation along the fiber axis originates from the migration of chain defects in the early stages of crystallization in the shear-field. The lengths of the needle crystals are approximately three times higher than those of the distorted zones. The values of the interface lengths between crystals and zones of lower electron density, are matching well with the lengths of the distorted zones. This result confirms the concept of defect clustering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01410319
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  • 2
    Electronic Resource
    Electronic Resource
    X-ray investigations of the formation of core-fibrils crystallized out of the oriented melt (1988)
    Springer
    Colloid & polymer science 266 (1988), S. 411-418 
    Details
    ISSN: 1435-1536
    Keywords: Core-fibrils ; crystallization models ; fiber morphology ; X-ray analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Crystallization models for the formation of core-fibrils crystallized from the oriented melt are discussed by comparing results from X-ray experiments with theoretical predictions. Two sets of polymer blends, the systems iPP/PB-1 and iPP/aPP have been measured. From wide angle X-ray scattering, the thicknesses of the core-fibrils, lattice distortions, and unit-cell parameters have been determined. Interface distribution functions have been used to evaluate the axial morphology of the fibers from meridional small angle X-ray scattering curves. It appears that the morphological predictions made by the crystallization models of Pennings and of Hoffman cannot be confirmed by the experimental findings. The diffusion model proposed by Petermann partially describes the morphological properties of the core-fibrils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01457257
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  • 3
    Electronic Resource
    Electronic Resource
    Isoelectronic Arduengo-Type Carbene Analogues with the Group IIIa Elements Boron, Aluminum, Gallium, and Indium (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 305-310 
    Details
    ISSN: 1434-1948
    Keywords: Ab initio calculations ; Carbene homologues ; Boron ; Isoelectronic analogues ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: While Arduengo-type carbenes are now well established for the Group IVa elements carbon, silicon and germanium, they are experimentally unknown for the isoelectronic anions with the Group IIIa elements boron, aluminum, gallium, and indium. In the present quantum chemical investigations, the bonding features of this class of compounds are explored. As a result, they are predicted to be stable species with sizeable singlet-triplet energy separations and electron affinities. Hence, they may be considered as valid targets for experimental investigations. An analysis of the electron density distribution in the case of boron and aluminum reveals a strongly polar B-N bond for the former, and a half Al-N bond with positive charge at the aluminum, emphasizing the donor-acceptor formulation for the latter.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis, Structure and Reactivity of 3,4-Dihydro-2H-1,2,4,3-triazaboroles (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1193-1198 
    Details
    ISSN: 1434-1948
    Keywords: Boron ; Triazaboroles ; Heterocycles ; Halogens ; Cyanides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3,4-Dihydro-2,4-diphenyl-2H-1,2,4,3-triazaboroles 3a, 3b, and 4 were synthesized by cyclocondensation of N1,N3-diphenylformamidrazone (1) with dibromophenylborane, dibromomethylborane, and boron trichloride. 3-Chloro-3,4-dihydro-2,4-diphenyl-2H-1,2,4,3-triazaborole (4) was converted into 3,4-dihydro-2,4-diphenyl-2H-1,2,4,3-triazaborole (5) by treatment with LiAlH4. The corresponding 3-cyanato and 3-cyano derivatives 6 and 7 resulted from the reaction of 4 with AgOCN and AgCN, respectively. Compound 7 was transformed into the bis(1,2,4,3-triazaborolyl)oxane 8 by silver oxide. Compounds 1-8 were characterized by elemental analyses and spectroscopic methods (1H, 11B, and 13C NMR; IR; MS). The molecular structure of 8 was established by single-crystal X-ray diffraction analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Substituent Effects on Folding in Cyclotetraphosphane (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1369-1371 
    Details
    ISSN: 0009-2940
    Keywords: Cyclotetraphosphanes, substituent effects, vibrational analysis ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio quantum chemical calculations evidence a very flat potential hypersurface for folding of parent cyclotetraphosphane. This is in accord with a corresponding vibrational analysis. Electronegative substituents increase folding of the fourmembered ring system.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240610
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  • 6
    Electronic Resource
    Electronic Resource
    Monomere und dimere 1,3-Diaza-2-phosphaallyllithium-Komplexe: Strukturen und ambidente ReaktivitätHerrn Professor Hans-Friedrich Grützmacher zum 60. Geburtstag gewidmet. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1119-1124 
    Details
    ISSN: 0009-2940
    Keywords: 1,3-Diaza-2-phosphaallyllithium ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monomer and Dimer 1,3-Diaza-2-phosphaallyllithium Complexes: Structures and Ambident Reactivity*Metallation of the NH-functional amino(imino)phosphanes Mes*NPNHR (R = CPh3, Ad, tBu) 1a-c yields the 1,3-diaza-2-phosphaallyllithium compounds 2a-c. The crystal structure shows an ether-stabilized monomer of 2a and a solvent-free dimer with an eight-membered ring in the case of 2b, c. The reaction of 2b with chlorodiphenylphosphane yields, dependent on the reaction conditions, (phosphanylamino)iminophosphane 3 or bis(imino)phosphanylphosphorane 4. The structural and reactivity is discussed on the basis of ab initio calculations.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250522
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  • 7
    Electronic Resource
    Electronic Resource
    [n + 2]-Cycloadditionsreaktionen des (Arylimino)phosphenium-Ions, [P≡NAr]+-kationische PN-Heterocyclen mit ungewöhnlicher Struktur und BindungssituationHerrn Professor Eckehard Volker Dehmlow zum 60. Geburtstag gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1513-1517 
    Details
    ISSN: 0009-2940
    Keywords: [n + 2] Cycloadditions ; Calculations, ab initio ; Phosphenium ions ; 1,3,2,4-Diazadiphosphetidinylium salts ; Tetrazaphospholylium salts ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [n + 2] Cycloaddition Reactions of the (Arylimino)phosphenium Ion, [P≡NAr]+-Kationic PN Heterocycles with Unusual Structure and Bonding SituationThe iminophosphenium ion [P≡NAr]+ (Ar=2,4,6-tBu3C6H2) (1) reacts with aminoiminophosphanes R2N-P=NtBu (R=iPr, Me3Si) (2) and alkyl azides RN3 (R=tBu, Et3C) (6) to yield the corresponding [n + 2] cycloadducts [R2NP (NAr)P(NtBu)+ (3) and [PN(Ar)NNN(R)]+ (7), respectively. Single-crystal X-ray diffraction studies show that 3a can be considered as an intramolecular donor-acceptor complex while 7 can be regarded as a cyclic diaminophosphenium cation coupled to a diimine fragment, which is in accordance with results of ab initio calculations.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260703
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