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  • Polymer and Materials Science  (4,864)
  • Life and Medical Sciences  (1,423)
  • Chemical Engineering  (983)
  • Biochemistry and Biotechnology  (602)
  • Engineering
  • 1985-1989  (6,103)
  • 1965-1969  (2,217)
  • 1950-1954
  • 1987  (6,103)
  • 1968  (2,217)
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  • 1985-1989  (6,103)
  • 1965-1969  (2,217)
  • 1950-1954
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  • 101
    Electronic Resource
    Electronic Resource
    Conformations of bioactive peptides: Cyclolinopeptide ADedicated to the memory of Professor F. Weygand. (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 2099-2101 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360261209
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  • 102
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    Masthead (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260001
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  • 103
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    To honor Ephraim Katchalski-Katzir (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. Siii 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260003
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  • 104
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    Bicyclic peptides. V. Conformation and ion binding of an undeca and a dodeca bicyclic peptideFor the previous paper in this series, see Ref. 7This paper is dedicated to Professor Ephraim Katzir on the occasion of his 70th birthday. (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. S11 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ion binding characteristics of two bicyclic peptides, cyclo(Lys-Pro-Gly-Pro-Gly-Glu-Pro-Gly-Pro-Gly)-cyclo(1ε → 6γ) Gly (BCP7) and cyclo(Lys-Pro-Gly-Pro-Gly-Glu-Pro-Gly-Pro-Gly)-cyclo(1ε → 6γ) Gly-Gly (BCP8) in a lipophilic solvent, acetonitrile, have been studied using CD and nmr spectroscopy. The data indicate that both BCP7 and BCP8 preferentially bind divalent ions. The nmr data showed that the conformation of both peptides in the free state was an average of many rapidly interconverting conformational states. The nmr titration data for Ca+2 ions with BCP7 and BCP8 indicated that both of these bicyclic peptides bind to calcium ions forming stable 1 : 1 and possibly 1 : 2 Ca+2:BCP-type complexes. The conformation of the Ca+2:BCP7 and Ca+2:BCP8 complexes were similar, with each containing two type I β-turns, one cis X-Pro bond and three trans X-Pro bonds. In the 1 : 1 complex, the Ca+2 ion coordinates to four carbonyl oxygens from the face opposite the bridgehead peptide as well as to two carbonyl oxygens from the interior of the cavity.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260006
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  • 105
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    Structural transitions in myosin and the origin of contractile force in muscle (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. S81 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Force generation in actively contracting muscle very likely involves a structural transition in each cycling cross-bridge while it is attached to actin. Two different types of force-generating mechanisms are discussed in this paper: (1) the force-generating event results from a change in the effective angle of the myosin head (S-1 subunit) and (2) a conformational change in the α-helical S-2 region of the crossbridge occurs when this portion of the bridge is released from the thick-filament surface. This process causes shortening in S-2 and produces force. Evidence supporting mechanism 2 has been obtained from recent studies of actively contracting muscle fibers and of isolated myosin rod subfragments using an enzyme- (chymotrypsin) probe technique to detect and pinpoint local melting within the α-helical structure. The kinetics of proteolysis and the site of cleavage were determined at various temperatures (5 to 40°C) by electrophoresis of digestion products on SDS gels. We found the cleavage sites to be localized in a restricted segment of S-2 spanning the LMM/HMM hinge region (64,000-90,000 Mr/polypeptide chain from the C-terminus of the myosin rod). The cleavage rate constant for activated muscle fibers in the presence of an ATP-regenerating system was about 100 times larger at each temperature than that for rigor or relaxed muscle fibers, and it showed a marked increase in magnitude with increasing temperature. Comparative plots of the apparent rate constant for cleavage within the S-2 hinge domain and the isometric force generated by active fibers vs MgATP concentration gave closely similar profiles, suggesting a close coupling between the conformational transitions within the S-2 hinge domain and contractile force when the cross-bridges undergo cycling.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360260010
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  • 106
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    Polymorphism of contractile proteins (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. S177 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Contractile proteins are present as multiple isoforms encoded by multigene families. The numbers of known isoforms of the myosins, actins, tropomyosins, and troponins are summarized, and the mechanisms by which this diversity has been generated are discussed. Two major strategies can be distinguished, one that depends on gene duplication events leading to the appearance of complete new structural genes, and a second that involves differential splicing of exons within a single complex gene. This latter mechanism is particularly prevalent among the contractile protein families. The developmental regulation of isoform expression is reviewed in the context of these strategies. The biological significance of contractile protein polymorphism is discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260016
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  • 107
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    The crystal structure of d(GGm5CCGGCC): The effect of methylation on A-DNA structure and stability (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. S145 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We describe the crystal structure of an octameric DNA sequence, d(GGm5CCGGCC), at 2.25 Å resolution. The sequence contains one C5-methylated cytosine per DNA strand. This methylation corresponds to that utilized in vivo by the HaeIII restriction modification system. The present structure is compared to that of the unmethylated octamer solved previously as well as to other A-DNA crystal structures. It retains the characteristics seen in these other DNA molecules, i.e., reduced base-pair tilt angles and increased major groove width, indicating that the presence of the methyl groups does not drastically affect the A-DNA backbone conformation. The position of the methyl groups appears to block the major grove, thus preventing potential sequence-specific protein interactions. In addition, the presence of these hydrophobic substituents may enhance the overall stability of the A-DNA conformation.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260014
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  • 108
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    The role of proline in the proteolytic regulation of biologically active peptides (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. S215 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Specificity studies of the enzymatic hydrolysis of proline-containing peptides give further evidence of the unique nature of the Xaa-Pro bond and indicate its role in the limited proteolysis as a structural element protecting the N-terminal chain end. A sensitive, highly specific fluorogenic assay was developed for aminopeptidase P [EC 3.4.11.9], that specifically cleaves N-terminal Xaa-Pro bonds. Examples of polypeptides with known N-terminal Xaa-Pro sequences are listed and the influence of proline on the proteolytic processing of polypeptide precursors is discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260019
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  • 109
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    Polynucleotide base-pair orientation in solution: Linear dichroism and molecular mechanical studies of poly[d(A)]-poly[d(T)] (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 1941-1956 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Model helices for poly[d(A)]-poly[d(T)] in solution were constructed based on the base orientations determined by linear dichroism [LD; S. P. Edmondson & W. C. Johnson, Jr. (1985) Biopolymers 24, 824-841] and refined by molecular mechanical energy minimization. The results demonstrate that poly[d(A)]-poly[d(T)] can form energetically stable conformations with the base orientations measured by LD. Further, only one of the four possible base-pair orientations that are consistent with the LD results is feasible. Models with negative base tilts had large potential energies, indicating that the LD results do not reflect base motions. The LD models of poly[d(A)]-poly[d(T)] are stabilized mainly by intrastrand base-stacking interactions, particularly for the adenine strand.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360261108
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  • 110
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    Phenomenological and mathematical analysis of the orientation in biaxially drawn polymeric films (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1021-1034 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Equations are derived that relate the orientation of “pseudo-affine” reoriented structural units after a biaxial deformation to the degrees and the directions of the effective drawings. The connection between these drawing parameters and those externally applied is analyzed in detail. It is shown how a comparison of these two sets of drawing parameters allows conclusions regarding the distribution throughout the material of the stresses that cause the deformation, the inhomogeneity of the deformation, and the role of non-orienting flow during deformation. In particular, the orientation of biaxially drawn poly(ethylene terephthalate) films is investigated, and it is shown what general information can be obtained on the deformation behavior of this material on the basis of these considerations.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271402
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  • 111
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    Scale-up of single screw extruders (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1059-1068 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Scale-up from small laboratory size extruders to large production size extruders is a procedure of great practical importance. Many scale-up rules and theories have been proposed in the past, however it is not always clear how the different scale-up methods will affect extruder performance. A basic analysis of scale-up in plasticating single screw extruders is developed from which the effect of a certain scale-up strategy on extrusion performance can be evaluated in terms of solids conveying, melting, melt conveying, mixing, residence time, heat transfer, power consumption, and specific energy consumption. Various existing scale-up theories are evaluated and compared using the basic analysis. A number of existing scale-up theories have some significant drawbacks, in particular with non-constant specific energy consumption and imbalance between melting rate and pumping rate. Conditions that are desirable to achieve in scale-up are enumerated and ranked in terms of importance. This leads to two new scale-up methods that result in constant mechanical specific energy consumption and high throughput rates. The first scale-up method keeps the specific surface area constant. This scale-up should work well for high values of the Brinkman number. However, at low values of the Brinkman number, the melting rate may be insufficient. The second scale-up method keeps the melting rate at low Brinkman number equal to the pumping rate and, thus, should be useful in cases where the first scale-up method cannot be used.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271406
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  • 112
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    Masthead (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271501
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  • 113
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    Fracture toughness and crack instability in tough polymers under plane strain conditions (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1128-1136 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 plane strain fracture toughness and fracture mechanisms of several tough engineering plastics have been studied and compared with poly(methyl methacrylate) (PMMA), a relatively brittle polymer. The tough polymers all are observed to form a multiple craze zone at the crack tip, which is shown to be the primary source of plane strain fracture toughness in these materials. The multiple craze zone is retained during slow crack growth but is metastable, and at a critical stress intensity and associated crack velocity, the system passes through a transition to a greatly accelerated single craze mode of unstable propagation.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271504
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  • 114
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    The optical properties of bisphenol-A polycarbonate (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1148-1155 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 optical properties of bisphenol-A polycarbonate resin as described by the complex index of refraction, N = n - ik, are derived by Kramers-Kronig analysis of experimental absorption and reflectance data obtained in the range 40μm ≥ λ ≥ 105 nm. Electronic absorption processes in polycarbonate are characterized by two broad absorption peaks centered at ∼200 and ∼100 nm.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760271507
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  • 115
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    Structure-property relationships in blends of linear low- and conventional low-density polyethylene as blown films (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1182-1186 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Three-layer coextruded blown (either blend or composite) films, made of low-density polyethylene and linear lowdensity polyethylene (1:1 ratio) of identical density, were compared. The tensile properties of both systems are nearly as high as those of the linear polyethylene while high strain rate properties including impact strength and tear resistance of the composite film are superior. Some structural insight was obtained by thermal analysis and thermoelastic measurements. Structure property relationships are discussed in light of the unique behavior, structure, and morphology of linear low-density polyethylene. The two polyethylenes are only compatible to a rather limited extent mainly affecting their blend behavior. However, a strong mutual reinforcement effect was observed.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760271511
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  • 116
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    Effects of strain-induced crystallization on the elastic and thermoelastic properties of some fluoroelastomers (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1203-1208 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: A Viton copolymer containing vinylidene fluoride (VF2) and hexafluoropropylene (HFP), and a terpolymer containing VF2, HFP, and tetrafluoroethylene (TFE) were cross linked using varying amounts of Bisphenol AF to yield two series of fluoroelastomer networks, Stress-strain isotherms in elongation were determined for these samples at several temperatures and at two degrees of swelling with phenyl acetate. Strain-induced crystallization was observed, as evidenced by upturns in the isotherms at high elongations. It appears to be more pronounced in the terpolymer samples, presumably because the TFE units not only can crystallize themselves, but can co-crystallize with the VF2 units. The crystallization was found to persist upon moderate increase in temperature, but was suppressed when the networks were swollen, Thermoelastic (force-temperature) measurements were used to obtain values of the fraction fe/f of the elastic force that is due to energetic effects. Negative values were obtained for both types of samples and, in the case of two samples studied in detail, their magnitudes increased with increase in elongation. The magnitudes were larger and the increases more pronounced in the case of the terpolymer networks, as would be expected from a greater tendency for straininduced crystallization.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271514
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  • 117
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    Transesterification reactions in molten polymers (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1221-1228 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 transesterification reaction of molten ethylene and vinyl alcohol copolymers (EVA), in presence of paraffinic alcohols and basic catalysts, leads to high conversion of the ester groups to secondary alcohol in both discontinuous and continuous processing equipment. Various kinds of alcohols and two different catalysts were used. Sodium methoxide is a powerful catalyst for the equilibrated transesterification reaction, but we also observed side reactions, such as cross-linking with low-molecular-weight alcohols and hydrolysis of the catalyst followed by partial saponification of the EVA. Kinetic studies were performed in the presence of dibutyltin dilaurate, an efficient catalyst without any side reactions. The solubility of the main alcohol reagents was verified by diffusion measurements. The general reaction scheme and the related kinetics, corresponding to a homogeneous system, lead to a fair evaluation of the rate constants.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760271604
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  • 118
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    Analysis of reaction injection molding process of polyurethane-unsaturated polyester blends. Part II: Mechanical properties (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1252-1257 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 mechanical properties of polyurethane-unsaturated polyester interpenetrating polymer networks (IPNs) that were prepared by reaction injection molding (RIM) process were measured with variations In composition, cross-link density, and relative reaction rate. From dynamic mechanical analysis (DMA), it was found that the two component polymers had a good compatibility over the whole composition range. The tensile strengths of the blends were greater than those of the pure components and had a maximum value at 50/50 composition. The modulus of elasticity and surface hardness decreased and the impact strength increased as the polyurethane content was increased, but the changes were not high at low polyurethane content, below 50%. For higher cross-link density, the compatibility was enhanced and the mechanical properties were improved. When the reaction rates of the components were different, some extent of phase separation was found in DMA and the properties were affected adversely.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760271608
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  • 119
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    Conductivity and spectroscopic characterization of polyacetylene doped with ferric chloride (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 349-355 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: cis- and trans-PolyacetyleneSystematic name: (Z)- and (E)-poly(viny1ene). films prepared by a rare-earth coordination catalyst were doped with ferric chloride in nitromethane solution. The doped polyacetylene films [CH(FeCl4)y]x exhibit high electrical conductivities which change very little when stored in dry air. Infra-red absorption bands at 900 cm-1, 1300 cm-1 and 1400 cm-1 are typical for cis-and trans-polyacetylenes slightly doped with FeCl3. In the samples with dopant mole fractions y 〈 0,02, two superimposed ESR signals with different g values are observed: one very narrow, the other one extraordinarily broad. 57Fe-Mössbauer effect measurements reveal that Fe(II) and Fe(III) species coexist in freshly doped cis-polyacetylene, appearing in the form of FeCl2 · nH2O and FeCl-4, respectively. Fe(II) species do not interact with the polyacetylene chain; they exist at a site separated from Fe(III) species.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880212
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    X-ray studies on phospholipid bilayers, 7.Part 6: cf.5. Structure determination of oriented films of L-α-dimyristoylphosphatidylethanolamine (DMPE) (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 599-606 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The bilayer structure of the phospholipid L-α-dimyristoylphosphatidylethanolamine (DMPE) was determined by X-ray diffraction fiber methods. This study was carried out on oriented films at different degrees of hydration at room temperature (about 19°C). DMPE molecules pack very closely with their two hydrocarbon chains almost fully extended and coplanar with their polar group, which lies perpendicular to the chains. It was found that the unit cell dimensions of DMPE did not vary appreciably between 0 and 86% relative humidity nor did its longest axis with an excess of water. The methods and techniques used to prepare the specimens and to solve the structure are described.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880312
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    Polyacrylate graft polymers prepared by grafting of monomethoxypoly(ethylene oxide) homopolymers onto acrylic acid: Self-gelling polymers (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 593-598 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polyacrylates of monomethoxypoly(ethylene oxide)Systematic name for MePEO: α-hydro-ω-methoxypoly(oxyethylene). (MePEO) were prepared by grafting MePEO on prepolymerized acryloyl chloride polymers of different molecular weights. Copolymers with carboxyl groups were also prepared by the addition of both water and MePEO. The polymers spontaneously form irreversible gels in water as soon as the degree of polymerization exceeds a certain limit. This gel formation confirms preceding results on similar polymers obtained by polymerization of MePEO acrylate and methacrylate macromonomers. It is concluded that the gelification phenomenon is not due to chemical cross-linking but rather to the presence of a high density of strongly interacting grafts of PEO on the polymer backbone. This new type of self-gelling system is considered to be of special interest.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880311
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  • 122
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    Studies on the nature of order in a rigid random copolymer (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 651-663 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The transition from the nematic melt to the solid state in a rigid rod-like copolymer was found to be characterized by unusual thermodynamic and kinetic properties. The transition occurred with negligible volume changes. The enthalpy and the entropy of the transition were found to be lower by at least one order of magnitude in comparison to the values usually observed for a crystal to nematic transition. The ordered solid state displays a glass transition and its structure is characterized by high symmetry, i.e., an orthorhombic one. Dielectric relaxation studies, investigations on the plastic flow properties of the solid state and studies on the dynamical mechanical properties revealed a high degree of rotational freedom already at room temperature in the solid state. These experimental findings led us to the conclusion that the solid state displays a three-dimensional positional long range order but is rotationally disordered with respect to rotations about the long axes of the rod-like molecules. The structure is similar to those of plastic crystals known for spherical molecules such as cyclopentane, or to smectic E modifications known for rod-like molecules. Also the properties reported above for the rod-like copolymers resemble those reported in the literature for plastic crystals.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880317
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    Preparative synthesis of guanylate-rich fragments of the terminal sequence of macronuclear DNA from hypotrichous ciliates using the phosphotriester method in solutionDedicated to Prof. Dr. E. Bayer on the occasion of his 60th birthday (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1313-1346 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Guanylate-rich oligodeoxyribonucleotides d(G4T4), d(T4G4), d(T4G4T4), d(G4T4G4), and d(T4G4T4G4) were synthesized in amounts up to 350 mg using the triester method in solution. These oligonucleotides correspond to fragments of the terminal of macronuclear DNA from hypotrichous ciliates. The protected oligonucleotides were obtained by block-condensation of protected 5′-hydroxyl and 3′-phosphate derivatives. Mixtures of 2,4,6-triisopropylbenzenesulfonyl chloride/N-methylimidazole or 2,4,6-trimethylbenzenesulfonyl chloride/N-methylimidazole were used as condensating agents. Different concepts of protecting the nucleotides were investigated and it was found that yields and purities of the resulting oligonucleotides do not depend essentially on the employed concept. The 36mer d(G4T4G4T4G4T4G4T4G4) was obtained by enzymatic phosphorylation of aliquots of the dodecamers d(G4T4G4) and d(T4G4T4), followed by ligation with T4 DNA ligase.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880609
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    Synthesis and characterization of vinyl monomers with blocked isocyanato groups (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1367-1373 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Vinyl monomers containing blocked isocyanato groups were prepared in one step, by blocking the isocyanato group of 2-isocyanatoethyl methacrylate with phenol, propanone oxime, butanone oxime, benzophenone oxime or ε-caprolactam, or in two steps, by blocking one of the two isocyanato groups of 4-methyl-1,3-phenylene diisocyanate with phenol or ε-caprolactam and the second group with 2-hydroxyethyl methacrylate. The 1H NMR and the IR spectra of these monomers are discussed.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880612
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    Compatibilité de polymères porteurs de groupements amides tertiaires avec le poly(difluoro-1,1 éthylène). Etude par enthalpimétrie différentielle (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1391-1401 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The miscibility of poly(1,1-difluoroethylene) (1) with poly(N-vinyl-2-pyrrolidone) poly(N-methyl-N-vinylacetamide) and poly(N,N-dimethylacrylamide), containing tert-amido groups, was investigated by differential scanning calorimetry. Amorphous homogeneous blends were obtained whenever the weight fractions of polymer 1 is less than 0,7. The dependence of the single glass transition temperature (Tg) versus composition may be readily analyzed either through the Gordon-Taylor equation (high values of the k parameter, suggesting strong specific interactions between the homopolymers) or by means of the Couchman relation (no adjustable parameter). The broadening of the glass transition range and the variation of the increment of specific heat at Tg for the blends are discussed.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880615
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  • 126
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    Electrochemical and chemical syntheses and doping of [poly(2,2′-dithienyl)-5,5′-diylvinylene] (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1425-1430 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The electroconductive polymer poly[(2,2′-dithienyl)-5,5′-diylvinylene] (1) was prepared by both electrochemical and chemical methods starting from trans-di(2-thienyl)ethylene (2). The electrochemically prepared material showed electrical conductivities of up to 40 Ω-1 · cm-1; the neutral, chemically prepared polymer was droped with iodine or arsenic pentafluoride but the conductivities were low. The experimental procedures are described and an interpretation of the results is given.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880618
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    Morphologie makroporöser 4-vinylpyridin/divinylbenzol-copolymereHerrn Prof. Dr. Manecke zum 70. Geburtstag gewidmet (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1447-1463 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Methods for the preparation of macroporous poly(4-vinylpyridine/divinylbenzene) resins with very different structures are described and the process of polymerization is discussed. The resins were prepared by suspension polymerization. The divinylbenzene content was varied between 8 and 25 mol-% and dioctyl phthalate, heptane, toluene, and mixtures of these solvents have been used as porogenic agents. The morphology of the resins was determined by mercury porosimetry, BET surface measurements, and electron scanning microscopy. By the use of aliphatic porogenic agents high pore diameters up to 9000 Å and surface areas of at least 17 m2/g resin were found whereas by the use of aromatic solvents like toluene resins of low pore size and surface areas up to 88 m2/g were obtained.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880620
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  • 128
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    Polylactones, 11H. R. Kricheldorf, R. Dunsing, A. Serra i Albet; Macromolecules in press.. Cationic copolymerization of glycolide with L,L-dilactide (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1861-1873 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Copolymerizations of glycolide with L,L-dilactide were conducted in chloroform, 1,2-dichloroethane and nitrobenzene. Chlorosulfonic acid, triflic acid, boron trifluoride, triethyloxonium tetrafluoroborate, but mainly methyl triflate, were used as initiators. 50°C was found to be an optimum reaction temperature, because higher temperatures resulted in dark coloured products of low viscosities. The composition of the copolyesters was determined by 1H NMR spectroscopy and the sequences by 13C NMR spectroscopy. Dyad splitting of the carbonyl signals allowed an accurate calculation of average block lengths. Under all circumstances glycolide showed a higher rate of incorporation, and truely random sequences were never obtained. However, the relative reactivities of both monomers largely depend on the nature of the initiator. The best results with regard to random sequences were obtained in 1,2-dichloroethane with methyl triflate (rG = 10,5 and rL = 0,9) and with triflic acid (rG = 14,0 and rL = 0,5). DSC measurements revealed that most samples possess crystalline domains of polyglycolide blocks. Nonetheless, many samples are soluble in hexafluoro-2-propanol and the amorphous samples also in dichloromethane or chloroform.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880810
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    Polymere Aminoschutzgruppen. Synthese von neuen poly[2-(N-vinylpyridinio)ethoxycarbonyl]-,2-(N-pyridinio)ethoxycarbonyl- und 2-(N-4-picolinio)ethoxycarbonyl-geschützten Aminoderivaten und kinetische Untersuchungen zur basisch induzierten Aminosäurefreisetzung (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2047-2059 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 2-Bromoethoxycarbonyl modified amino acids were reacted with pyridine, 4-picoline and poly(4-vinylpyridine) to yield the corresponding 2-(N-pyridinio)ethoxycarbonyl derivatives as water-soluble amino-protecting groups. The kinetics and activation energies of basicly induced cleavage of the amino acids were investigated by 1H NMR spectroscopy in a D2O/NaOD medium. The polymeric salts were found to be more reactive than the low molecular weight pyridinium bromides because of electrostatic polymeric effects. Additionally, the kinetic measurements confirmed a E1cB mechanism for the cleavage of the urethane function. The formation of peptide bonds was performed in the case of poly[2-(N-4-vinylpyridinioethoxycarbonyl)]-protected amino acids in aqueous medium by water-soluble carbodiimides.
    Additional Material: 5 Tab.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880904
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    The synthesis of poly(allylamine) containing covalently bound cyclodextrin and its catalytic effect in the hydrolysis of phenyl esters (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2071-2082 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A poly(allylamine) {poly[1-(aminomethyl)ethylene]} (2) containing covalently bound β-cyclodextrin (CD) residues (3) was synthesized. The inclusion ability of CD was enhanced in this polymer 3. A pronounced catalytic acceleration of the hydrolysis of p- and m-nitrophenyl acetate by 3 as compared with that of 2 indicates the cooperative effect of CD and amino groups on the polymer chains.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880906
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    Polymères porteurs de dérivés du glycérol, 7.Partie 6: cf.1.. Synthèse d'esters d'époxy-2,3 propyle (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 35-45 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 2,3-Epoxypropyl esters were obtained in two steps from carboxylic acids or in one step from their alkali salts by reaction with 1-chloro-2,3-epoxypropane or from the acid chloride with 2,3-epoxy-1-propanol. The kinetic parameters of these reactions were studied with acetic acid and sodium acetate to evaluate the optimal conditions for the synthesis of these esters with the intention to apply them to polymers containing carboxylic groups.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880104
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    Experimental evidence for the regiospecific primary mode of styrene insertion into metal-carbon bonds of an isospecific Ziegler-Natta catalyst (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 21-33 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Styrene/1-hexene copolymers of different chemical composition were prepared with a classical isospecific Ziegler-Natta catalyst, TiCl3(H)-AlEt3. Their structure and the distribution of the monomeric unites was analyzed by GPC double detection and 1H and 13C NMR. The chemical arrangement of isolated and blocked styrene monomeric units between sequences of hexene monomeric units was also investigated. 13C chemical shifts of carbon atoms in the copolymers and in addition in model molecules of the two modes of styrene addition indicate that styrene insertion into carbon-metal bonds of the catalyst proceeds according to a primary mode. Mechanistic implications of these results are discussed.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880103
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    Chain packing in two aromatic heterocyclic polymers, one of which has a ladder structure (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 455-455 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880221
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    Phase-transfer catalysis of phosphonium ions derived from poly[(P-phenyl)trimethylenephosphine]Dedicated to Prof. G. Manecke on his 70th birthday (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 457-462 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymeric phosphonium ion species having different content of phosphonium units (4a and 4b) were prepared from poly[(P-phenyl)trimethylenephosphine] (3). Phase-transfer catalysis of 4 was examined by means of a typical SN2 reaction (1) in a bi-phase system. The apparent rate constant (kobs) was determined, its magnitude being smaller by about one order than that of the corresponding monomeric phosphonium ion 5. Crosslinked polymeric phosphonium ion species were coated on powdery alumina and used as a phase-transfer catalyst for reaction (1) in a triphase system. Due to the inhomogeneous reaction, the kobs value was much smaller (1/5) than that in presence of 4.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880301
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    Cationic ring opening polymerization of 4,5-dihydro-2-[2-(9-anthryl)ethyl]-1,3-oxazoleDedicated to Professor Charles G. Overberger on the occasion of his 65th birthday (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 505-511 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new monomer, 4,5-dihydro-2-[2-(9-anthryl)ethyl]-1,3-oxazole (5) was synthesized and polymerized by cationic ring-opening isomerization. The polymerization was carried out in bulk or in solution, using methyl tosylate, ethylene ditosylate and α-tosyl-ω-tosyloxypoly(oxyethylene) [poly(ethylene oxide)ditosylate] as initiators. The polymers were characterized by IR, 1H NMR and UV spectroscopy.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880305
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    Transfer by weak acids in the slow-initiation-no-termination (SINT) polymerization of butyl cyanoacrylateDedicated to Prof. Dr. Georg Manecke for his 70th birthday (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 527-536 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The theory of slow-initiation-no-termination polymerization has been extended to take account of transfer by added or adventitious transfer agents (T), giving equations relating the number-average molecular weight (M̄n) to the ratios of concentrations of transfer agent to monomer ([T]0/[M]0) and of transfer to propagation rate constants (ktr/kp). The equations are shown to give a fair description of the M̄n values found in the polymerization of butyl cyanoacrylate by pyridine and by tetrabutylammonium acetate in presence of known concentrations of cyanoacetic, chloroacetic and acetic acids. Approximate values are yielded for the rate constant ratios, viz. 102(ktr/kp) ≈ 15,5 and 0,3, respectively (in tetrahydrofuran at 20°C). Conversely, the theory is shown to explain variations in M̄n values found in polymerizations of five different samples of this monomer, permitting characterization of the unknown concentrations of transfer-causing impurity.
    Additional Material: 5 Tab.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880307
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    Computer simulation of the steady state in reversible polymer-analogous reactions, 2.Part 1: Cf.9. Simulation of the statistics in detailed balance (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 155-170 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The steady state of reversible polymer-analogous reactions is simulated by Monte Carlo methods. Two types of sets of relative rate constants were investigated, first, K1 = K2 = K3, K1 · K3 = (K2)2, and second, K1 ≠ K2, K1 ≠ K3, K2 ≠ K3, K1 · K3 = (K2)2. For both cases a detailed balance was found. The sequence probabilities depend on dimensionless relative rate constants Kn only, while the rates of sequence flow depend on reaction probabilities p and ordinary rate constants k. For the first case, the sequence probabilities obey a Bernoullian statistics, while for the second case a first-order Markov statistics is found.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880114
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    Measurement of conversion in free radical copolymerization from dilatometric data (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 189-199 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In order to evaluate copolymerization rates from dilatometric measurements, the relationship between volume contraction and conversion (dilatometric constant) must be investigated. This can be done gravimetrically or by means of density measurements. In cases where one of the monomers is not able to homopolymerize, both methods lead to different values. Equations necessary for this evaluation were derived and verified in the systems diethyl maleate-methyl methacrylate and diethyl maleate-styrene. In some cases, the dependence of the dilatometric constant on feed composition may be predicted taking into account the contributions to volume contraction of the different bond types present in the copolymer. An expression was derived for describing this dependence in cases where one of the monomers does not homopolymerize. Its validity for the system diethyl maleate-styrene was experimentally verified.
    Additional Material: 8 Ill.
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    A composite model for the thermal conductivity of semicrystalline polymers (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 217-226 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A phenomenological model is proposed which considers the polymer as an aggregate of units. The units are composed of two distinct phases  -  amorphous and crystalline. The thermal conductivity of a unit is calculated in terms of those of its constituents. In the undrawn state these units are distributed randomly, and the isotropic thermal conductivity of the bulk results. The development of strong anisotropy in thermal conductivity is explained in terms of the preferred orientation of these units. The structural features of this model are similar to those employed for the interpretation of the mechanical properties. The change in orientation of the units was deduced from the experimental data of birefringence. Finally, the results obtained from the composite model for several semicrystalline polymers are compared with the experimental data and other existing calculations. The model is found to give a fair overall description of the thermal conductivity in the cases of polypropylene, polyoxymethylene, low and high density polyethylene, and polychlorotrifluoroethylene.
    Additional Material: 4 Ill.
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    Precursors of hydrophilic polymers, 7Part 6: cf.4.. Potentiometric properties and structure of copolymers of 2-dimethylaminoethyl methacrylate (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 227-238 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The study concerns the potentiometric behaviour of statistical copolymers of 2-dimethylaminoethyl methacrylate with 2-hydroxyethyl methacrylate, acrylamide, methacrylamide, 2-methacryloyloxyethyltrimethylammonium methylsulfate, and of copolymers arising by the partial quaternization of poly(2-dimethylaminoethyl methacrylate) with methyl iodide in various water-ethanolic solutions. The potentiometric properties of poly(4-dimethylaminobutyl methacrylate) and poly(6-dimethylaminohexyl methacrylate) are also reported. The course of modified titration curves and the differences between pK0 values of copolymers and pK values of low-molecular weight model compounds are discussed. Side chains of copolymers of 2-dimethylaminoethyl methacrylate have a cyclic conformation (similarly to the homopolymer); the carbonyl and amine group interact with each other. Copolymers formed by the partial quaternization of poly(2-dimethylaminoethyl methacrylate) with methyl iodide in a water-ethanolic medium (Menshutkin's reaction) have a block structure, which suggests a zip mechanism of the quaternization reaction.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880201
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    Announcement (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 3060-3060 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021881226
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    Zerlegung von hemicellulosereichem biologischem material mit wasser in einem strömungsreaktor (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 749-762 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Biological materials, rich in hemicelluloses (birch and pine wood, wheat straw and rice hulls) were disintegrated batchwise in a flow reactor with pure water at elevated temperatures and pressures. The resulting extractives and residual fibre compounds were characterized. Because of rapid removal of carbohydrate based extractives from the hot reaction zone, the degradation of pentosans and hexosans to furfural and hydroxymethylfurfural could be limited to only a small amount. Contrary to normal prehydrolysis conditions employing a sealed batch reactor, temperatures of 190 to 210°C and residence times of goods of 60 min are the optimum. Thus, hemicelluloses are dissolved and isolated with up to more than 90% yield. At temperatures above 225°C severe destruction of hemicelluloses and solvolysis of cellulose starts. Depending on disintegration temperatures, pentosan average molecular weights (M̄w) vary in case of birch wood between 3800 at 150°C and 900 at 225°C. The content of monomers rises with temperature and reaches a maximum of 45% at 225°C. DPw of residual cellulose is also temperature dependent and varies in case of birch wood and wheat straw between 1500 and 450. Lignin, which is mostly not dissolved, can be removed almost quantitatively by further treatment of the residue with ethanol/water at 250°C, thus allowing the isolation of relatively pure cellulose.
    Additional Material: 4 Ill.
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    Ion exchange and ring-opening reactions of telechelic poly(tetrahydrofuran)s containing terminal cyclic quaternary ammonium salts (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 783-789 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Anion exchange and ring-opening reactions of cyclic quaternary ammonium salt end groups of poly(tetrahydrofuran) [poly(THF)] were studied. The counter anion exchange reaction of the quaternary ammonium triflate to the sulfonate or to the carboxylate, was found to take place by precipitation of the starting poly(THF) prepolymer from an aqueous solution containing the corresponding sodium salt. The azetidinium salt 1 was found to undergo ring opening reaction with its carboxylate counter ion at ambient temperature, whereas the pyrrolidinium salt 2 needs heating up to 100°C. The ring-opening reactivities of the cyclic ammonium salts of poly(THF) chain ends were compared with those of model systems.
    Additional Material: 5 Ill.
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    Polymers with pendant carbazolyl groups, 2.Part 1: cf.18. Synthesis and characterization of some novel liquid crystalline polysiloxanes (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 811-820 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The synthesis of the liquid crystalline polysiloxanes 8a-c is reported. In these polymers carbazolyl groups are incorporated in the mesogenic units. 8a-c were prepared from the Schiff's bases 7a-c and poly(hydrogenmethylsiloxane) in a polymer analogous reaction. The liquid crystalline polymers were characterized by DSC and polarizing microscopy. The Schiff's bases 7a-c are nematic, whereas the polysiloxanes 8a-c exhibit smectic mesophases within a broad temperature range. Unfortunately, the polymers show no remarkable increase of conductivity upon illumination.
    Additional Material: 4 Ill.
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    Über Abbaureaktionen bei der alkalischen Hydrolyse von Polyacrylsäureestern in Dimethylsulfoxid (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1047-1054 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The alkaline hydrolysis of some methyl methacrylate-ethyl acrylate copolymers in alkaline dimethyl sulfoxide leads to products containing carboxyl groups and having molecular weights which are significantly lower than those of the original copolymers. Size exclusion chromatographic (SEC) investigations provide detailed information on the degree of degradation and the influence of hydrolysis rate on degradation. Comparing the reactivities of structural units it is assumed that the degradation reaction occurs at the ethyl acrylate units.
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    Effect of glass transition on catalytic activity of polymer-anchored rhodium complexes (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1085-1093 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A rhodium complex was anchored upon three types of phosphinated polystyrene which were crosslinked with divinylbenzene or ethylene dimethacrylate. Glass transitions were separately observed for the flexible polymer supports and their polymer-anchored rhodium complex catalysts using differential scanning calorimetry. Discontinuous activity drops in the Arrhenius plot for the ethylene hydrogenation reaction were observed for these flexibe polymer catalysts, while, for the rhodium complex anchored on a highly crosslinked rigid polymer, neither glass transition nor such a discontinuity in the catalytic activity could be detected. This reversible activity drop is discussed in terms of changes in the stability and the coordination state of the ethylene complex influenced by the micro-Brownian motion of the polymer network.
    Additional Material: 7 Ill.
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    Flow properties of concentrated solutions of polyarylate in m-cresol (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1129-1136 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The flow properties of concentrated solutions of polyarylate from bisphenol A/50:50 isophthalic acid: terephthalic acid in m-cresol are studied. The results are discussed in terms of critical concentration Cc and critical molecular weight Mc for the onset of entanglements. Values of Cc = 8,2 wt.-% and Mc ≈ 3500 are obtained. The dependence of the Newtonian viscosities with temperature allows to obtain different energies of activation of flow for each polyarylate/m-cresol system, ranging from 9 to 13 kcal/mol (= 37,7 to 54,4 kJ/mol). The following free-volume-additivity equation is proposed to fit these data: \documentclass{article}\pagestyle{empty}\begin{document}$ E_{\rm a} = \frac{{V_{\rm p} \cdot \alpha _{\rm p} \cdot E_{{\rm ap}} + V_{\rm d} \cdot \alpha _{\rm d} \cdot E_{{\rm ad}} }}{{V_{\rm p} \cdot \alpha _{\rm p} + V_{\rm d} \cdot \alpha _{\rm d} }} $\end{document} where Ea, Eap, and Ead are the activation energies of the solution, the polymer and the solvent, respectively. Vp and Vd are the polymer volume fraction and the diluent volume fraction, respectively, and αp and αd represent the differences between the volume coefficients of expansion above and below the corresponding glass transition temperatures for the polymer and the solvent.
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    Evidence of crosslinks in a butadiene-divinylbenzene-ethylvinylbenzene copolymer by metathesis degradation (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2481-2488 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 1,3-Butadiene was copolymerized with a mixture of divinylbenzene isomers containing ethyl-vinylbenzene isomers. The crosslinked copolymers were degraded in a cross metathesis reaction with (Z)-2-butene or (E)-3-hexene using the catalyst WCl6/Sn(CH3)4. The low-molecular-weight products were investigated by gas chromatography/mass spectrometry coupling. Products containing the crosslinks were found. Others were attributable to copolymer units resulting from butadiene and ethylvinylbenzene. Characteristic mass spectra of the products are discussed.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021881022
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    New synthesis of polysulfide polymers: Kinetic study (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2517-2522 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: New polysulfide polymers were prepared by a new process from vinyl monomers, elemental sulfur, and sodium metal in THF. The kinetic study of the reactions at -40°C has shown that the overall process can be described by the competition between a slow reaction (initiation of the monomer by the alkali metal) and a fast reaction (deactivation of the carbanion formed by elemental sulfur). These reactions lead to the establishment of a carbanion stationary state. From this data, the orders of magnitude of the apparent deactivation rates of the different carbanions were obtained: ca. 105 1·mol-1·s-1 for the styrene carbanion and 103-104 1·mol-1·s-1 for the butadiene carbanion.
    Additional Material: 2 Ill.
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    Moisture-curable rubbers, 4Part 3: cf.4.. Moisture-cure of chloroprene rubber (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2553-2557 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Chloroprene rubber (CR) was allowed to react with 3-aminopropyltriethoxysilane (APS) and then cured by soaking in hot water. The moisture-cured rubber showed a network-chain density of 3,6·10-4 mol·cm-3 and a tensile strength at break of 10 MPa. The reaction of CR with APS was found to be a Menshutkin reaction. The activation energy and the frequency factor were 59 kJ·mol-1 and 4,3·104 l·mol-1·s-1, respectively.
    Additional Material: 4 Ill.
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    Réactivité du groupement N-(époxy-2,3 propyl)-N-méthylamino vis-à-vis d'amines aromatiques à l'état fondu. Etude des mécanismes et des chemins réactionnels (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2559-2572 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mechanism and kinetics of the reactions of N-(2,3-epoxypropyl)-N-methylaniline (1) with aniline or 4,4′-sulfonyldianiline (3) were investigated using high performance liquid chromatography and 13C FT NMR under different conditions (110-172°C). Comparison of 1 with its derivatives shows that the activity of the 2,3-epoxypropyl group in such epoxides depends on the structure and the substituents at the benzene ring; etherification may occur already before the secondary amine is consumed.
    Additional Material: 8 Ill.
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    Three-phase carboxylation reactions of poly(chloromethylstyrene) beads with sodium nitrite (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1383-1389 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The formation of carboxylic acid groups (carboxyl + ester groups) was found in a threephase reaction of crosslinked poly(chloromethylstyrene) beads with an excess amount of sodium nitrite in immiscible solvents of benzene and water with tetrabutylammonium bromide as a phase transfer catalyst (PTC), and the dependence of carboxylic acid yield on the experimental conditions was studied. The product contains hydroxyl groups and ester bonds besides carboxyl groups. It was tentatively considered that the carboxyl groups are produced by direct oxidation of chloromethylstyrene groups by nitrous anions. Nitrous anions do not only act as a nucleophile but also as an oxidative reagent in this case.
    Additional Material: 4 Ill.
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    Synthese und Komplexierungseigenschaften von monomeren und polymeren 5-Methacryloylaminosalicylsäure-Derivaten (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1641-1650 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The synthesis of monomeric and polymeric 5-methacryloylaminosalicylic acid derivatives is described. The interaction of these ligands with Fe(III), Ti (IV) and Ca(II) ions was investigated by photometric, conductometric and viscosimetric measurements.
    Additional Material: 4 Ill.
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    Studies on formaldehyde resins, 25Part 24: cf.2. Kinetic study on the hydroxymethylation of melamine by means of HPLC (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1683-1688 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of hydroxymethylation of melamine (2,4,6-triamino-1,3,5-triazine) with formaldehyde to form N-(hydroxymethyl)melamine (2,4-diamino-6-hydroxymethylamino-1,3,5-triazine) was investigated in aqueous hydrogen phosphate/phosphate buffer solutions in the range of pH 10,51 to 12,20 at 20°C, determining unreacted melamine by means of HPLC. As a result, this reaction is subject to a general base catalysis, and the second order rate constant k is expressed by k = k′ + kA - [A-] + kp″[A-]2/[HA] (or kp‴ [A-][OH-]), where HA and A- denote acid and basic constituents of the buffer, and k′ is the rate constant in unbuffered media. This rate equation is compared with those reported previously.
    Additional Material: 5 Ill.
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    Dielectric properties of a combined main-chain/side-chain liquid-crystalline polymer (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1501-1509 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dielectric relaxation properties of a combined main-chain/side-chain liquid-crystalline polymer were investigated. It was found that the rotation of the side chain about the main chain (δ-process) is not as strongly restricted as in side-chain liquid-crystalline polymers. This is attributed to the facts that the side chain is attached to the flexible spacer within the chain backbone and that the concentration of the side chains is comparatively small. Two low-temperature relaxation processes were observed to occur in the glassy smectic and the crystalline state. They are attributed to intramolecular motions with in the mesogenic groups.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880624
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    Synthesis and characterization of biaxial nematic side chain polymers with laterally attached mesogenic groups (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1597-1611 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The synthesis and characterization of liquid crystalline side chain polymers with mesogenic groups laterally attached to the polymer main chain are described. By variation of the terminal group, mesogenic moiety or spacer length, a change in the glass transition temperature, the nematic to isotropic transformation temperature and the stability of the nematic phase can be achieved. With increasing length of terminal groups, a distinct odd-even effect of the nematic to isotropic phase transformation temperature and also a strong decrease of the glass transition temperature is observed. Macroscopic homeotropic alignment can be achieved in an electric or magnetic field. Conoscopic investigations show optical biaxial behavior of the nematic phase. A chiral nematic copolymer is the first example of a thermotropic biaxial cholesteric phase.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880706
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    Novel synthetic approach to poly(p-benzenesulfonamide): Self-polycondensation of active p-aminobenzenesulfonic acid derivatives under mild conditions (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2839-2846 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Three active p-aminobenzenesulfonic acid derivatives, 1-(p-aminobenzenesulfonyl)imidazole (4a), 1-(p-aminobenzenesulfonyloxy)benzotriazole (4b), and 2-phenyl-4-(p-aminobenzenesulfonyl)-1,3,4-oxadiazoline-5-thione (4c) were synthesized by reacting p-isocyanatobenzenesulfonyl chloride (1) with stoichiometrical quantities of water in the presence of dibutyltin didodecanoate and subsequently with imidazole, 1-hydroxybenzotriazole and 2-phenyl-1,3,4-oxadiazoline-5-thione, respectively. The self-polycondensation of 4a-c, leading to poly(p-benzenesulfonamide) (7), was carried out in solution using polar aprotic solvents, N-methyl-2-pyrrolidone (NMP) and hexamethylphosphoric triamide (HMPA), and acidic media, dimethyl sulfoxide (DMSO) and m-cresol, with or without an appropriate acid catalyst or acid acceptor under mild conditions. Poly(p-benzenesulfonamide) having the highest reduced viscosity of 0,14 dl·-1 was obtained almost quantitatively from 4c by using m-cresol as a solvent without any acid catalyst and acid acceptor at 25°C. The polymers are soluble in polar aprotic solvents such as NMP, HMPA and DMSO and in aqueous sodium hydroxide. These poly(p-benzenesulfonamide)s are less thermally stable than completely aromatic polyamides, because the initial weight-loss started at 250-350°C. Aminolysis of three benzenesulfonic acid derivatives, 1-benzenesulfonylimidazole (5a), 1-benzenesulfonyloxybenzotriazole (5b), and 2-phenyl-4-benzenesulfonyl-1,3,4-oxadiazoline-5-thione (5c), with the same leaving groups was also carried out as a model reaction of self-polycondensation to determine the reaction conditions.
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    Design of vinyl functional copolymers with main chain chirality through chemical modifications (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2847-2856 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Optically active poly(styrene-co-methyl methacrylate) and poly(styrene-co-methacrylonitrile) were obtained by means of asymmetric copolymerization of 3,4-cyclohexylidene-D-mannitol-1,2; 5,6-bis{O-[(4-vinylphenyl)boronate]} (1) with methyl methacrylate and methacrylonitrile, respectively, removal of the D-mannitol template and splitting off boric acid from the resulting copolymers. By polymer analogous reactions, various functional groups were introduced to obtain optically active functional vinyl copolymers. The polymers were characterized by spectral and other analytical methods.
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    Rigid rod polymers with flexible side chains, 4Part 3: cf.3.. Synthesis, structure and phase behaviour of polyimides prepared from pyromellitic anhydride and 2,5-di-n-alkoxy-1,4-phenylene diisocyantes (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2865-2873 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of rigid rod polyimides 1a-f derived from pyromellitic anhydride (PMDA) and 2,5-di-n-alkoxy-1,4-phenylenediamine containing flexible alkoxy side chains with 4 to 16 carbon atoms was prepared by solution polycondensation. As demonstrated by model experiments full conversion to the imide structure is achieved by reaction of PMDA with 2,5-dialkoxyphenylene diisocyanate, the latter compound being blocked by imidazole. The best solvent for the polycondensation, found in the course of the model reaction, is 1,3-dimethyl-2-oxo-perhydro-pyrimidine together with 4-dimethylaminopyridine as an accelerator. Wide-angle X-ray diffractograms showed that all polyimides under consideration here are highly crystalline at room temperature. The occurrence of a sharp reflection at the region of low angles together with its higher orders demonstrates the presence of a layered structure. The layer spacing was found to increase linearly with the length of the alkyl side chains. Polyimides bearing long side chains (n ≥ 10) exhibit two broad endotherms in the DSC analysis. As is revealed by wide-angle X-ray analysis the first transition is related to a disordering process of the side chains. The second transition leads to a layered high-temperature phase akin to the modification (B) found in a recent study of a similar rigid polyester bearing flexible side chains.
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    Anodic polymerization of acrylamide in aqueous nitrate solution using an activated iridium electrode (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2885-2893 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The flow of an electric current through an aqueous solution of acrylamide and NaNO3, using an activated iridium electrode as anode, induces the polymerization of the monomer in solution. The influence of the chemical and electrochemical variables on monomer conversion was studied. The experimental results point to the production of initiating radicals by charge transfer between the electrolyte and the electrode, followed by desorption of these radicals from the electrode into the solution. The electrode process is a mixed process in which all the species present take part. Electrode activation depolarizes the NO-3 discharge and increases the polymerization rate.
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    Comportement au voisinage des conditions «théta» des solutions semidiluées et concentrées de poly(diméthylsiloxane) dans le styrène (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2921-2934 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermodynamical properties of poly(dimethylsiloxane) (PDMS) were studied in the theta-solvent styrene. Moderately diluted and semidiluted solutions of three PDMS samples with weight-average molecular weights M̄w = 23 500, 160 000, and 860 000 were investigated by means of light scattering near the theta-temperature. The dependency of the interaction parameter X on temperature and concentration was established for the three samples. The study of the third virial coefficient A3 showed that A3 is independent of molecular weight and temperature as predicted by theory. However, the experimental value of A3/(A22M) was higher than expected. The critical properties, i.e., critical point and spinodal, were considered.
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    ESR determination of rate constants for the radical polymerization of methyl phenethyl itaconate (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2951-2961 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Phenethyl 2-(methoxycarbonylmethyl)acrylate (methyl penethyl itaconate) (1) was prepared and its polymerization with dimethyl 2,2′-azoisobutyrate (2) was investigated kinetically in benzene. The polymerization rate (Rp) was found to be expressed by Rp = k·[2]0,5·[1]1,8 (at 50°C). Further, a higher dependence of Rp (2nd order) on the concentration of 1 was observed at 61°C. The overall activation energy of the polymerization was calculated to be a low value of 50,3 kJ/mol. The initiator efficiency (f) of 2 was determined to be 0,48 to 0,22 at 50°Cand 0,50 to 0,28 at 61°C. f decreases with increasing monomer concentration due to the high viscosity of 1. The poly(1) radical is stable enough to be observable by ESR at high temperatures (50-60°C). Rate constants of propagation (kp) and termination (kt) were estimated using the poly(1) radical concentration determined by ESR. kp [6,0 to 121/(mol·s) at 50°Cand 7,1 to 15 1/(mol·s) at 61°C] shows a trend to increase with the concentration of 1. On the other hand, kt [2,9·104 to 17·1041/(mol·s) at 50°Cand 6,9·104 to 45·1041/(mol. s) at 61°C] decreases with increasing MPI concentration. This behavior is responsible for the high order with respect to monomer concentration. Copolymerization of 1 (M1) with styrene (M2) at 50°Cgave the following results: r1 = 0,36, r2 = 0,40, Q1 = 0,82 and e1 = + 0,59. Using the above results, the rate constants of the cross-propagations were estimated to be k12 = 22 1/(mol·s) and k21 = 308 1/(mol·s) at 50°C.
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    Photosensitive polymers with pendent p-dialkylaminobenzylideneacetophenone residues as photoinduced radical polymerization initiators (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2983-2993 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymers with pendent p-dialkylaminobenzylideneracetophenone (PABA) groups were prepared by copolymerization of 4-(4-dimethylaminobenzylidenemethylcarbonyl)phenyl methacrylate (1) with alkyl methacrylates and by the substitution reaction of poly(chloromethylstyrene-co-methyl methacrylate) with sodium 4-(4-dimethylaminobenzylidenemethylcarbonyl)phenolate (3). The polymers having PABA groups become insoluble upon photodimerization of PABA. Furthermore, the photosensitivity of the polymers increases considerably when mixed with vinyl monomers and diphenyliodonium hexafluorophosphate (DPI) during irradiation. The photocrosslinking may involve graft polymerization initiated by PABA which sensitizes the decomposition of DPI to form radicals. Introduction of unsaturated groups like maleate or crotonyl groups into the PABA polymer depresses the shrinkage of the photocured polymer film when the polymer was mixed with DPI. Sensitivity characteristics of PABA polymers toward Ar laser emitting 488 nm light are mentioned.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021881219
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    Spezifische Adsorbentien für das Peptidantibiotika synthetisierende Enzymsystem Gramicidin S Synthetase, 2Teil 1: cf.7.. Kupplung niedermolekularer Spacer/Ligand-Verbindungen mit reaktiven polymeren Trägern und Untersuchung der Adsorptionswechselwirkung dieser polymeren Produkte mit Gramcidin S Synthetase (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 3017-3028 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The inhibition constants (KI) of aliphatic and aromatic amide derivatives of phenylalanine and proline for GS1 and GS2 of the enzyme system gramicidin S synthetase were determined. These compounds act as competitive inhibitors. Some of these compounds (spacer/ligand compounds) were reacted with epoxy-activated Sekpharose 6B or with crosslinked poly(vinyl alcohol). The resulting - for GS1 or GS2 more or less specific - adsorption materials, were used for the purification of these multi-enzyme systems.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021881222
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    Crystallization, morphology, and thermal behaviour of ethylene/propylene copolymers (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2231-2239 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The morphology and the texture of thin films of ethylene/propylene copolymers with crystallizable polypropylene blocks was investigated by optical and electron microscopy as a function of both molecular composition and crystallization conditions. The thermal and melting behaviour was also studied. It was found that variables such as the observed melting point as well as the enthalpy and the entropy of fusion are composition dependent. Contrary, the equilibrium melting temperature seems to be invariant with composition in agreement with the block type of the investigated copolymers.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021880920
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    An unexpected mode of cationic oligomerization of 1-vinyl-4,5,6,7-tetrahydroindole (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2251-2257 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 1-Vinyl-4,5,6,7-tetrahydroindole in the presence of Brønsted acids (HCl, H2SO4, HOAc) and Lewis acids (BF3 · OEt2, FeCl3, TiCl3, SnCl4, SiCl4, Et3SiCl, Me2, PhMeSiCl2) undergoes an alternative oligomerization involving both the double bond and the α-position of the pyrrole ring to form the dimer 1-vinyl-2-[1-(4,5,6,7-tetrahydro-1-indolyl)ethyl]-4,5,6,7-tetrahydroindole in a yield up to 68% and oligomers of the same backbone, soluble (major product) and insoluble (minor product) in hot hexane, the latter being enriched by oxidized and hydrolyzed tetrahydroindole units. The molecular weights of the former oligomers were assessed from 1H NMR spectra to range from 1000 to 2000.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021881001
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    Immobilisierung von geschützten nucleosiden und mononucleotiden an funktionalisierte perlcopolymerisationsprodukte aus methylacrylat und 1,4-bis(vinyloxy)butan (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2277-2291 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Protected nucleic acid components were coupled to eight differently functionalized bead copolymers, prepared from methyl acrylate and 1,4-bis(vinyloxy)butane, via amid-, urea-, phosphotriester- or carboxylic acid ester linkages. The immobilization was performed by methods used in nucleic acid chemistry. The obtained gels carry 1 to 300 μmol per gram of nucleoside or nucleotide derivatives. The yield of derivatization was found to be first of all determined by steric effects of the gel matrix, the size of the nucleic acid component and the route of synthesis selected. Anchor groups, arranged via long spacers, were not effective for the immobilization of nucleic acid components. A “carboxylate-gel” which can immobilize 300 μmol per gram of a nucleoside derivative may serve as support in the solid phase synthesis of oligonucleotides in large scale.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/macp.1987.021881004
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    Quaternization of poly(N-tert-butyliminoethylene)Dedicated to the memory of Prof. Tom St. Pierre (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2293-2300 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(N-tert-butyliminoethylene) was quaternized with several agents. Only the very reactive methyl trifluoromethanesulfonate allowed to attain relatively high quaternization degrees after short reaction times. The maximum degree of quaternization was 0,44. This was attributed to the complete lack of reactivity of amino functions which have a quaternized neighbour. By means of 1H NMR spectroscopy it was possible to measure the fractions of the different triads and . Analysis, by means of Monte Carlo calculations, of the relative amount of these triads as a function of the degree of quaternization lead to the conclusion that the reactivity of the first, second and third nitrogen next to an ammonium function is 0,0,20 and 0,57, respectively, the reactivity of a nitrogen in an ammonium-free chain being 1. This shows that the electrostatic deactivation exerts its action to at least nine atoms away from the charged atom. The quaternized polymer is unstable even at room temperature. After a few days the formation of isobutene is observed.
    Additional Material: 4 Ill.
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    Self-diffusion coefficient of flexible-chain polymers in solution and in the melt (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2353-2370 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A theory was developed for predicting the self-diffusion coefficients Dp of macromolecules and of oligomers in solution and in the melt. For moderate-concentration ranges account was taken of decreasing intramolecular hydrodynamic interaction with increasing concentration. In the high-concentration range the scaling theory was used. The dependence of Dp on concentration, molecular weight, and quality of the solvent was described by a common relationship as a function of √c[η] with mass concentration c and intrinsic viscosity [η]. If the dependence is considered in the form Dp ∝ cβ, then the value of the exponent β varies between 0 and 2. If the dependence of the local viscosity is taken into account, then β is greater than 2. An analysis of the relationships of Dp for oligomers and polymers in melts was also conducted. The theoretical results obtained describe quantitatively the available experimental data. These results were used for the interpretation of the decreasing decay rate of macroradicals with increasing conversion (gel effect).
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1987.021881011
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    Numerical methods for heat transfer in hydraulic fracturing (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 75-87 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: During the propagation of a hydraulically induced fracture in a porous material, fluid leak-off occurs from the fracture to the formation. Conduction and convection of heat also take place, owing to the large difference between the fluid injection temperature and that of the reservoir. The paper describes a quasi-two-dimensional heat transfer model coupled with a filtration model. It is then coupled into different coupled fracture propagation models (two-dimensional and quasi-three-dimensional).The rheological characteristics of the fracturing fluid are temperature-dependent with a sharp breakdown. The fluid diffusion model combines cake growth at the fracture face with two-fluid flow in the formation. Temperature profiles along the fracture and the formation are computed during fracture propagation.
    Additional Material: 11 Ill.
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    Numerical models for the thermo-mechanical evolution of Atlantic-type continental margins (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 141-157 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: We have developed a versatile finite element approach to analyse stresses and displacements induced in thermally thinned and thickened geological structures. Material and geometric non-linearities form an important aspect of the finite element simulation. The changes in geometry are incorporated by a multipoint constraint procedure. The method takes into account temperature-dependent variations in rheological properties of the medium, including the presence of a brittle-ductile transition. We illustrate the application of the method for specific geophysical problems associated with the temperature history of the earth's crust at continental margins of the Atlantic type.
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    A finite element method for free and forced convection heat transfer (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 117-128 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A new finite element method is presented. This new method contains several novel features including a streamline upwind formulation for the advection terms and equal order interpolations for all variables: velocities, pressure, temperature and other fluid properties. This new formulation uses an iterative solution method greatly reducing the computer storage requirements. The validity of the new finite element method was tested on both a natural convection problem, a thermally driven cavity, and a forced convection problem, a heated cylinder in cross-flow. The predicted results compared favourably with a benchmark solution for the cavity and an empirical correlation for the cylinder in cross-flow.
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    Announcement (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. i 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620240202
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    A new approach for the hybrid element method (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 1697-1709 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A new functional which forms the basis of an improved hybrid element formulation is proposed. The variables for the functional include stresses, strains and displacements, and the displacements and stresses are further decomposed into two parts respectively. The proposed new formulation appears to be particularly suitable for improving conforming models.Based on this formulation, a new four-node plane hybrid element Qcs6 can be developed, and the conforming element Q4 and the non-conforming Wilson element Q64 and modified Wilson element Qm6 can also be derived directly by this hybrid approach. It should be noted that more accurate stresses can be obtained from this element which utilizes the concept of two stress components.
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    Notes on the stability of non-rectangular space-time finite elements (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 1721-1739 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The method of space-time finite elements enables the simple solution of quite new problems. It is possible to assume the arbitrary partition of the structure area in each moment of integration of the motion equation. Instability is caused by a too large time step and too great changes of joint locations in successive time steps. A changeable spatial partition is useful in contact dynamic problems, in the case of a travelling support, generally in problems with movable edges. In this paper a stability problem is described and some investigations for chosen types of non-rectangular space-time finite elements are carried out. Linear and surface elements which in time space gain an additional time dimension are presented. Some numerical examples prove the efficiency of the described method under determined limitations.
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    Conference diary (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 659-661 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620240315
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    Masthead (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987) 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620240401
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    Practical stability analysis of finite difference equations by the matrix method (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 679-687 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: It is shown how the various norms of the coefficient matrix of a set of finite difference equations can, in many cases, be employed in an easy, straightforward fashion to find sufficient conditions for stability in situations involving non-periodic boundary conditions and variable coefficients. With the aid of the easily computed norms, particularly the infinite norm, one does not have to rely on the necessary condition provided by the spectral radius, which has been the main basis of criticism of the matrix method in the past.
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    Stress oscillations in plane stress modelling of flexure - a field-consistency interpretation (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 711-724 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Exactly integrated isoparametric plane stress elements behave poorly in flexure. The 4-noded element ‘locks’, with errors that progress indefinitely as element aspect ratio increases. Reduced integration of the shear strain energy eliminates this locking entirely. The 8-noded element does not lock, but improves in performance with reduced integration of shear strain energy. Both elements, with their original shape functions, show severe shear stress oscillations in flexure. In this paper we attribute these oscillations to the lack of ‘consistency’ of shear strain fields derived directly from independent field-variable interpolations. We derive error models for specific tractable examples which can confirm the accuracy of this conceptual scheme through digital computation using the finite element models. A field-consistent redistribution strategy for the shear strain field is offered as an elegant procedure to free the elements of spurious oscillations and give a ‘lock’-free performance.
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    The uniqueness characteristics of mixed finite element methods in linear elasticity (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 927-944 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Having established the non-uniqueness, in general, of quadratic-linear functionals in elasticity, the investigative work on this topic is reviewed, whence it is noted that there is no existing formal approach for the identification of either the causes of singular solutions or suitable remedial measures that might ensure their elimination. A comparison of the weighted averages obtained from the single field and Reissner's principles is then used to identify a higher order uniqueness criterion for the latter. A detailed consideration of the application of the new condition to the arch equations demonstrates how and why singular solutions can be obtained, and thence how suitable forms of remedial action can often be identified. Finally, several other classes of problem are briefly investigated in order to show how the criterion can be used to explain the full range of known behaviour of the mixed methods.
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    Multi-grid methods and applications, W. Hackbusch, Springer-Verlag (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 2036-2036 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
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    URL: http://dx.doi.org/10.1002/nme.1620241016
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    Masthead (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987) 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
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    URL: http://dx.doi.org/10.1002/nme.1620241101
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    Preconditioned conjugate gradient technique for the analysis of symmetric anisotropic structures (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 2057-2070 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An officient preconditioned conjugate gradient (PCG) technique and a computational procedure are presented for the analysis of symmetric anisotropic structures. The technique is based on selecting the preconditioning matrix as the orthotropic part of the global stiffness matrix of the structure, with all the nonorthotropic terms set equal to zero. This particular choice of the preconditioning matrix results in reducing the size of the analysis model of the anisotropic structure to that of the corresponding orthotropic structure. The similarities between the proposed PCG technique and a reduction technique previously presented by the authors are identified and exploited to generate from the PCG technique direct measures for the sensitivity of the different response quantities to the non-orthotropic (anisotropic) material coefficients of the structure. The effectiveness of the PCG technique is demonstrated by means of a numerical example of an anisotropic cylindrical panel.
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    Announcement (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 1232-1232 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
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    URL: http://dx.doi.org/10.1002/nme.1620240620
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    Masthead (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987) 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
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    URL: http://dx.doi.org/10.1002/nme.1620240701
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    Numerical simulation of confined unsteady aerodynamical flows (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 1233-1250 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A system of algorithms is presented for the computer simulation of confined unsteady flows of a compressible fluid. The methods are valid for a wide range of time scales and are applied to simulate wind tunnel acoustics, flow over a ramp and flow past aircraft cavities.
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    A basis change strategy for the reduced gradient method and the optimum design of large structures (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 1269-1281 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper proposes a basis change strategy within the reduced gradient method for optimization under linear constraints. It ensures a non-singular basis matrix at every iteration. The same strategy can reliably be used within the generalized reduced gradient method for optimization under non-linear constraints. This method is applied to the minimum weight design of large structures under displacement and stress constraints, exploiting the sparsity of the constraint Jacobian matrix.
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    A new boundary finite element method for fluid-structure interaction problems (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 1251-1267 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In order to study problems on fluid-structure interaction, we have used a mixed formulation which couples the classical functional of the structure with a new variational formulation by integral equations for the fluid. This formulation has the advantage over the finite element methods of avoiding the discretization of the fluid domain. Furthermore, unlike collocation methods, the explicit calculation of the Hadamard finite part of the singular integrals is avoided. This leads after discretization by boundary finite elements to a small and symmetrical algebraic system.Typical examples are presented that demonstrate the efficiency of this variational formulation by studying the sound transmission through a baffled plane structure and through a flexible panel backed by a rigid cavity. These include the calculation of the transmission loss factor and the determination of which modes dominate the noise transmission. Good agreement is obtained between numerical results and analytical results found in the literature.
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    Numerical experiments on turbulent flow using the random vortex method (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 1297-1303 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Chorin's random vortex method is used to predict the growth of a large-scale coherent vortex structure in the early stages of the development of turbulence in a two-dimensional co-flowing shear layer. The numerical algorithm has been simplified to such an extent that the numerical analysis can be performed on a microcomputer. The numerical solution exhibits the same early turbulent instabilities and vorticity pairings as found in recent flow-visualization experiments. In addition the results are in reasonable agreement with experimental measurements of mean velocity, root mean square fluctuations and Reynolds stresses. One could thus test the shear layer sensitivity to initial conditions and the upsteam boundary conditions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620240706
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    Stability convergence and accuracy of the DuFort and Frankel difference diagram approximating a class of non-linear parabolic field equations (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 1421-1437 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The paper presents a method of calculation for the transient electromagnetic field in a steel rotor screen of a superconducting generator. Using the difference method, the spatial-temporal distributions of the electromagnetic field have been calculated as a result of solving the non-linear partial differential equation for the vector potential A (in space Ω(r, θ,t)). For the difference diagram the conditions of stability and convergence have been determined.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620240802
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  • 191
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    The space-time Sinc-Gallerkin method for parabolic problems (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 1629-1644 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper contains the formulation of a space-time Sinc-Galerkin method for the numerical solution of the parabolic partial differential equation in one space dimension. The space-time adjective means that the Galerkin technique is employed simultaneously in time and space. Salient features of the method include: exponential rate of convergence, ease of assembly of the discrete system, a global approximation and the ability to handle singular problems. Two methods of solution for the discrete system are offered and numerical results for test problems, selected from the literature, are included.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620240903
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    Isotropic plate elements with shear and normal strain deformations (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 1671-1695 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Plate-bending finite elements are developed for thin and moderately thick plates. The element takes into account the influence of the transverse normal strain and the transverse shear effects. For the computation of the stresses, an additional plate element is developed to determine the inplane displacements and forces. The combined effects of the plate-bending and inplane elements are used for the complete solution of the problem. Several examples are solved and compared with their corresponding exact solutions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620240906
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    Elastic strain effects during steady-state rolling of visco-elastic slabs (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 1659-1669 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The effect of elastic strains in the steady-state visco-elastic fluid flow under the rolling process is analysed quantitatively. Spurious oscillations in the stress deviator and pressure fields are precluded and the rate of convergence is improved when the Petrov-Galerkin method, which is based on a least-square method, is introduced into the finite element equation for the constitutive law.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620240905
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  • 194
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    Plotting of contours in a natural way (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 1757-1769 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A simple and straightforward scheme for plotting contours is introduced. For any function the appropriate contours are traced on the paths of constant function values disclosing the information contained in the shape functions. The exactness of the contours matches that of the finite element analysis. Extreme value considerations must be carried out to decide whether contours appear in an element at all. Three co-ordinate systems are dealt with: the local, the global and the screen co-ordinate system, and the necessary mutual transformations. A short section deals with the treatment of contour discontinuities across element borders which frequently occur with stresses and heat fluxes. Finally, some examples are shown.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620240911
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  • 195
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    A theorem regarding the locking of tapered four-noded membrane elements (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 1793-1799 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: It is shown that any four-noded membrane element with two degrees of freedom per node will either lock in inplane bending or fail to pass a C0 patch test when the element's shape is an isosceles trapezoid. This result effectively closes out further effort to extend the linear strain capability of such elements beyond what has already been achieved for rectangular and parallelogram shapes.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620240913
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  • 196
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    Calculation of fracture mechanics parameters for an arbitrary three-dimensional crack, by the ‘equivalent domain integral’ method (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 1801-1821 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In this paper, an equivalent domain integral (EDI) method and the attendant numerical algorithms are presented for the computation of a near-crack-tip field parameter, the vector J∊-integral, and its variation along the front of an arbitrary three-dimensional crack in a structural component. Account is taken of possible non-elastic strains present in the structure; in this case the near-tip J∊-values may be significantly different from the far-field values Jf, especially under non-proportional loading.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620240914
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    Masthead (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987) 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620241001
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    Computer algorithms for calculating efficient initial vectors for subspace iteration method (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 1841-1848 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In this paper, the effects of selecting initial vectors on computation efficiency for a subspace iteration method are investigated. Four algorithms are used for selecting the initial vectors. First, arbitrary starting iteration vectors are chosen according to Bathe and Wilson's algorithm.1 In the other algorithms, the initial vectors are the retrieved eigenvectors from the Guyan and quadratic reduction methods. Improvement of the eigenvalue approximations of the subspace iteration method over reduction methods is presented. The computation effort is examined for the various algorithms used for initial iteration vectors.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620241003
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    Professor Guy Sander (1937-1987) (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. iii 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620241102
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    Selective refinement: A new strategy for automatic node placement in graded triangular meshes (1987)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 24 (1987), S. 2183-2200 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Automating triangular finite element mesh generation involves two interrelated tasks: generatine a distribution of well-placed nodes on the boundary and in the interior of a domain, and constructing a triangulation of these nodes. For a given distribution of nodes, the Delaunay triangulation generally provides a suitable mesh, and Watson's algorithm26 provides a flexible means of constructing it. In this paper, a new method is described for automating node placement in a Delaunay triangulation by seieclive refinement of an initial triangulation. Grading of the mesh is controlled by an explicit or implicit node spacing function. Although this paper describes the technique only in the planar context, the method generalizes to three dimensions as well.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620241111
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