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  • 1
    Electronic Resource
    Electronic Resource
    Bifunctional Catalysis of Ester Aminolysis - A Computational and Experimental Study (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 1501-1509 
    Details
    ISSN: 0947-3440
    Keywords: Aminolysis ; Esters ; Pyridones ; Catalysis ; Calculations, ab initio ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various pathways for the reaction of methylamine with methyl acetate catalyzed by 2(1H)-pyridone have been investigated at the Becke3LYP/6-31G**/HF/6-31G** level of theory. The most favorable pathway consists of a one-step reaction, in which all bond-forming and -breaking processes occur in concert. These modeling studies also show the pyridone to function as an acid, which led to the investigation of several substituted pyridones. 4-Cyano-, 3-cyano-6-methyl-, and 3-cyano-2(1H)-pyridone have indeed been shown to provide better catalysis in the ester aminolysis reaction by ab initio modeling at the Becke3LYP/6-31G**/HF/3-21G level. In order to verify the theoretical results, the catalytic activities of various substituted 2-pyridones in the reaction of n-butylamine with p-nitrophenyl acetate in chlorobenzene solution have been determined. The observed catalytic rate constants are indeed in agreement with the theoretical predictions. Other catalyst characteristics such as solubility and state of aggregation are, however, also of paramount importance in this reaction.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961003
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  • 2
    Electronic Resource
    Electronic Resource
    Thin films of nylon 13,13 casted on water: Morphology and properties (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 785-790 
    Details
    ISSN: 0887-6266
    Keywords: nylon ; nylon 13,13 ; cast film ; thin films ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Substrate-free thin film of Nylon 13,13 has been prepared continuously by casting the polymer on a water surface from m-cresol solution. The uniform thickness of film is ca. 500 A, as measured with a Profilometer. Film morphology and properties have been characterized by transmission electronic microscopy (TEM), x-ray photoelectron spectroscopy, wide-angle x-ray scattering, differential scanning calorimetry and by contact angle measurements. Results show that there is no preferential accumulation of the amide group toward the water surface. A spherulite structure exists in this film with a crystallinity of 26% by DSC. Fibers were drawn from the films which had a tensile modulus of 5 GPa, stiffer than reported for this nylon as prepared by other means. Other members of the nylon series, such as Nylon 6, Nylon 12, have also been prepared in films by the same casting method under modified conditions. © 1995 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090330507
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  • 3
    Electronic Resource
    Electronic Resource
    Infrared studies of transesterification in poly(ethylene terephthalate)/polycarbonate blends (1986)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 7 (1986), S. 255-259 
    Details
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1986.030070504
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  • 4
    Electronic Resource
    Electronic Resource
    Hard elasticity of polyethylene formed by cold-drawing and annealing (1987)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 8 (1987), S. 539-542 
    Details
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1987.030081105
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  • 5
    Electronic Resource
    Electronic Resource
    Ultradrawing and crystallization of isotactic polystyrene and blends with atactic polystyrene (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 2373-2379 
    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: Pure isotactic polystyrene (iPS, Mw = 8.89 × 104, Mw/Mn = 4.89) and its blends with an atactic polystyrene (aPS, Mw = 3.9 × 105, Mw/Mn 〈 1.13) were subjected to draw by solid state coextrusion at 127°C within polyethylene. The content of amorphous iPS in these blends was varied from 100 to 24.4 wt %. The extent of draw-induced crystallization was found to depend on the draw ratio and on iPS concentration. The blend with 24.4% iPS was coextruded in two stages. The highest effective draw ratio (EDR) was 7.6 and 13.7 for one- and two-stage draw, respectively. The highest crystallinity of 33.2% was obtained for pure iPS at the maximum EDR of 7.6. Considerable crystallinity was induced in blends, requiring successively higher draw ratio to reach similar crystallinity with increased aPS content. The tensile modulus increased from 1.5 to 3.2 GPa, independent of iPS concentration. Thermal shrinkage results indicate that the elastic recovery of draw in the blends is near quantitative for an EDR 〈 8. For pure iPS, extrudate elastic recovery was dramatically altered by the draw-induced crystallinity.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1981.070260723
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  • 6
    Electronic Resource
    Electronic Resource
    The surface orientation of polystyrene measured by liquid contact angle (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 1439-1445 
    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: The surface contact angle of glycerol and of water on polystyrene (PS) films has been found to depend on the extent of uniaxial draw for atactic PS. The contact angle depends on direction for the smooth films of PS drawn by solid state coextrusion. Results as a function of draw ratio to values over 4 on these noncrystalline PS samples, Mw = 6 × 105, have also been interrelated with other measures of orientation such as the anisotropy of surface and bulk properties measured, respectively, by dichroic reflectance infrared spectroscopy and by birefringence.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1983.070280417
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  • 7
    Electronic Resource
    Electronic Resource
    Rolling and roll-drawing of ultrahigh molecular weight polyethylene reactor powders (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 1559-1564 
    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: Ultrahigh molecular weight polyethylene (UHMWPE) reactor powders have been found to be processable in the solid state by the techniques of rolling and roll-drawing. Plates of compacted UHMWPE reactor powder were prepared below their melting points. These plates were then rolled at 124°C. The maximum uniaxial draw ratio (DR) obtained by multiple rolling was about 10. In additional experiments, rolled plates of a DR of 6 were further drawn by tensile stretching at a temperature of 135°C. The specimens prepared by rolling and by the two-stage draw were characterized by tensile measurements, differential scanning calorimetry (DSC), and X-ray diffraction. Results show that, on rolling alone, the tensile modulus and tensile strength achieved were 3 GPa and 42 MPa, respectively, at a DR of 9.6. The rolled plates were effectively drawn further to a total DR of 86. Such highly drawn films exhibited tensile moduli and tensile strength up to 81 and 1.3 GPa, respectively. A high crystallinity and high crystal orientation were also obtained by the two-stage draw.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070430819
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  • 8
    Electronic Resource
    Electronic Resource
    Properties of polypropylene structural foam crosslinked by vinyltrimethoxy silane (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 4639-4647 
    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: Polypropylene containing the blowing agent azodicarbonate was first grafted with vinyl trimethoxy silane, then crosslinked using the hot water treatment. Two heating stages initiated the blowing agent and formed polypropylene structural foam. The effects of such reaction variables as initiator, cross-linking agent, cross-linking accelerator, and blowing agent on the gel fraction, density, and expansion ratio of polypropylene foam were studied. Furthermore, cell dimension, compression strength, and volume resistivity were also measured and analyzed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070320428
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  • 9
    Electronic Resource
    Electronic Resource
    Thermal expansion of ultradrawn polystyrene (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 633-640 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Measurements on the linear thermal expansivities α∥ and α⊥ parallel and perpendicular to the extrusion direction, respectively, have been carried out between -160 and 30°C for atactic polystyrene (aPS) with extrusion ratio 1 ≤λ≤ 15 and isotactic polystyrene (iPS) with 1 ≤λ≤ 7.5. For both aPS and iPS, α∥ decreases sharply with increasing λ whereas α⊥ shows only a slight increase. Below λ = 5 the anisotropy α⊥/α∥ is nearly the same for both, but α⊥/α∥ for iPS becomes much larger at higher λ. This is accompanied by an abrupt rise in crystallinity and probably results from the increase in the number and tautness of intercrystalline tie molecules. The birefringences of aPS and iPS increase with λ and have nearly the same values for λ 〈 5. At higher λ, however, there is a sharp rise in the birefringence of iPS which is probably associated with the sudden increase in crystallinity. With an aggregate model, the chain orientation function for aPS calculated from thermal expansivity is found to be in reasonable agreement with the corresponding value obtained from birefringence.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.180200406
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis of bis-ketene N,S-acetals with a polymethylene linkage (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 7 (1996), S. 285-288 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: α-Aroyl substituted bis-ketene N,S-acetals 3-6 with a polymethylene linkage, N,N′-bis(1-methylthio-2-aroyl)vinyl polymethylene diamines, were synthesized by reactions between α-aroyl ketene dithioacetals 1 and polymethylene diamines 2 in moderate yields. © 1996 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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