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  • 1985-1989  (4)
  • 1970-1974  (3)
  • 1960-1964
  • Polymer and Materials Science  (7)
  • 1
    Electronic Resource
    Electronic Resource
    Stereochemistry and dynamic behavior of some synthetic “angular” profisetinidin tetraflavanoid derivatives (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 835-849 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure and stereochemistry of four synthetic “angular” tetraflavanoid-condensed tannin derivatives are examined by high-resolution variable temperature 1H NMR. spectroscopy, and hence correlated with their dynamic behavior. Three “angular” oligomers exist as stable rotational isomers at ambient temperatures, thus contrasting with the mobility about their interflavanoid bonds of most natural profisetinidin “trimeric” and “tetrameric” homologs. A “linear” tetraflavanoid analog results from one of these regioselectively controlled condensations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240503
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Molecular weight distribution and rheological properties of polyisobutylene solutions (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1181-1194 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The molecular weight distribution of a series of polyisobutylenes was determined using osmotic pressure measurements, gel permeation chromatography, and intrinsic viscosity. All of the polymers except for one, a blend of the highest and lowest molecular weight constituents, had similar moderate molecular weight distributions. The “extended chain length” method of calibrating the gel permeation chromatograph for polyisobutylenes was found to be effective. Steady state and transient shear stresses and normal stresses were measured on 5% decalin solutions of these polymers. The zero shear viscosity increased with the 3.3 power of molecular weight, and the zero shear normal stress coefficient (σ11 - σ22)/Γ2 varied with the 7.5 power. Relative elastic memory as measured by (σ11 - σ22)/σ12 or stress relaxation increased with increasing molecular weight (and at constant number- or weight-average molecular weight) with breadth of distribution. Stress overshoot also correlated with this tendency.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1971.070150513
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Gel permeation and thin-layer chromatographic characterization and solution properties of butadiene and styrene homopolymers and copolymers (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 2811-2827 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Gel permeation chromatographic (GPC) and thin-layer chromatographic (TLC) studies of polystyrene, polybutadienes (BR), and their copolymers (SBR) have been carried out. GPC primarily separates them on the basis of molecular size, and TLC, on the basis of composition. Methods of obtaining absolute molecular weight distributions for BR and SBR based upon variations of the Strasbourg Universal Calibration procedure are described. In particular, [η]-M relationships in both the GPC solvent (THF) and in a second solvent (toluene) were used; in addition, results of statistical mechanical calculations for \documentclass{article}\pagestyle{empty}\begin{document}$\overline {s^2 }$\end{document} (based on the assumption of negligible steric hindrance and freely rotating bonds) were applied. An experimental comparison of these methods was carried out, and use of the [η]-M relationships for both solvents was found to give satisfactory results. The predictions of the statistical theory were too low. A detailed study of polymer-solvent-gel interaction in the GPC unit was made through investigation of ternary phase equilibrium in the (polystyrene)-THF-(polymer) system. The polymers studied included BR and SBR with varying styrene contents. Experimental techniques for TLC separations of BR, SBR, and polystyrene according to the composition are described.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1972.070161108
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Ligament and tendon substitution with composite carbon fiber strands (1986)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 20 (1986), S. 699-708 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Carbon fiber strands were used experimentally to substitute for tendons in dogs and clinically to reconstruct tendons and ligaments in human. The investigation was carried out to determine the histologic appearance of the new composite structure and its tensile strength in comparison to the natural structure. The histologic picture disclosed a remarkable structure evolved by continuous irritation of the carbon fibers and consisting of two interrelated components: synthetic carbon fibers and biologic collagenous tissue. This carbon fiber composite structure was composed of long cylindrical units containing concentric layers of collagenous fibers and cells enveloping the core of each carbon fiber. After one year of physiologic use in dogs, the average ultimate tensile strength of the composite structure which replaced the quadriceps and triceps was 372 N, or 88% the strength of the natural tendons. One year after implantation the histologic picture of the composite structure in human showed a relatively dense collagenous architecture. However, a significant proportion of the structure was taken up by histiofibroblasts produced by the irritation of the carbon fibers. Thus, the density of the collagen in the composite structure remained relatively deficient in comparison to the nature tendon, and the structural tensile strength continued to depend entirely on the integrity of the carbon fibers.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820200604
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  • 5
    Electronic Resource
    Electronic Resource
    The polymerisation of ethylene with high activity magnesium reduced titanium trichloride catalysts in the absence of hydrogen (1974)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 175 (1974), S. 3461-3473 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Polymerisation von Äthylen unter Verwendung eines mit Magnesium reduzierten Titantrichlorid-Katalysators, zusammen mit gewöhnlichen Aluminiumalkyl-Aktivatoren, wird beschrieben. Die bereits berichtete hohe Aktivität dieses Katalysatortyps wird bestätigt. Bei 50°C und 1 Atm. (1,01325 bar) Druck wird ein Wert für die Aktivitätskonstante von 3,4.106 g dm3 (mol TiCl3)-1 h-1 erhalten. Dieser Wert ist ungefähr 102 mal höher als derjenige eines auf übliche Weise mit Aluminium reduzierten Titantrichlorids. Die Viskosotäts-Molekulargewichts-Zeit (oder Umsatz)-Beziehungen sind nicht sehr verschieden von denen, die mit den üblichen Katalysatoren erhalten werden. Die Analyse der Resultate weist darauf hin, daß ein großer Teil (z. B. 50%) der Titan-Atome im Titantrichlorid, das mit Magnesium reduziert wurde, als aktive Zentren fungieren.
    Notes: The polymerisation of ethylene using magnesium reduced titanium trichloride catalysts, together with the usual aluminium alkyl activators is described. The previously reported high activity of this type of catalyst was confirmed. At 50°C and 1 atm. (1,01325 bar) pressure a value of 3,4.106 g dm3 (mol TiCl3)-1h-1 was obtained for the activity constant, a value about 102 times larger than for a conventional aluminium reduced TiCl3. On the other hand the viscosity-molecular weight-time (or conversion) relations are not very different from those given by conventional catalysts. Analysis of the results suggests that a high proportion (e.g. 50%) of the titanium atoms in the magnesium reduced TiCl3 functions as active sites.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1974.021751212
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  • 6
    Electronic Resource
    Electronic Resource
    Structure of native proteoglycan aggregates from chick limb-bud chondrocytes (1986)
    New York : Wiley-Blackwell
    Biopolymers 25 (1986), S. 931-946 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Laser light-scattering has been used to investigate the size of native proteoglycan aggregates (PGA-aA1) from day-8 chick limb-bud chondrocyte cultures isolated under associative extraction and purification conditions in 0.4M guanidinium chloride (GdnHCl) solution. Dynamic light-scattering measurements yielded a hydrodynamic radius, Rs, of 244 ± 10 nm for PGA-aA1 in 0.4M GdnHCl, and a weight-average molecular weight (Mw) of 150 ± 50 × 106 was obtained from a Zimm plot. Disaggregation in 4.0M GdnHCl aqueous solution yielded proteoglycan subunits (PGS) with Rs = 39 ± 2 nm, Mw = 1.6 ± 0.3 × 106, which reassembled in 0.4M GdnHCl to form “reconstituted native” aggregates (PGA-raA1) with Rs = 121 ± 6 nm, Mw = 17 ± 3 × 106. A second specimen of PGA-aA1 had Rs = 192 ± 10 nm, Mw = 100 ± 10 × 106. The latter value was estimated from an empirical relationship between Mw and Rs. After dissociation, this specimen reassembled to form PGA-raA1 with Rs = 85 ± 5 nm, Mw = 12 ± 1 × 106. These data are compared with those for a specimen of reconstituted aggregate (PGA-A1) that had been extracted under dissociative conditions and then reaggregated by dialysis to 0.4M GdnHCl aqueous solution, for which Rs = 138 ± 9 nm, Mw = 45 ± 8 × 106. From these values, we have calculated the weight-average number of subunits per aggregate Nw: 111 for PGA-aA1 and 12 for raA1 (70 and 7 for the second PGA-aA1 and PGA-raA1 specimen, respectively) as compared to 32 for PGA-A1. The numbers of subunits per aggregate were also determined from electron micrographs of spread specimens. The latter results show the same trends as those obtained by light scattering, but lead in each case to lower numbers of subunits per aggregate. These data demonstrate conclusively that PGA samples exhibit a higher degree of aggregation in solution than visualized in typical electron microscopy (EM) preparations, probably due to disaggregation during EM specimen preparation. Since Nw determined both by light scattering (LS) and by EM are larger for native versus reconstituted aggregate samples, our data point to a more compact aggregation of subunits along the hyaluronic acid (HA) chains in the former.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360250512
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  • 7
    Electronic Resource
    Electronic Resource
    A spin polarization analyzer attachment to a scanning auger microprobePaper presented at ECASIA 87, Stuttgart, FRG, 19-23 October 1987. (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 11 (1988), S. 605-610 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A new, compact electron spin polarization analyzer attachment to a scanning Auger microprobe has been described. Its operation and present performance has been demonstrated using the SEMPA technique to image the surface magnetic microstructure of three different types of magnetic samples. The unique advantages of SEMPA have been identified previously; those that were illustrated in these applications are: (1) the tecnique is surface sensitive; (2) the magnetic structure is imaged independently of the surface topography; (3) the contrast and signal are large; and (4) all three components of the polarization can be determined and therefore the surface magnetic vector can be mapped. Additionally, high spatial resolution can be achieved.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740111205
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