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  • Polymer and Materials Science  (8)
  • 1980-1984  (2)
  • 1975-1979  (6)
  • 1982  (2)
  • 1975  (6)
  • 1
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Light scattered from a macromolecular solution in a capillary tube is used to determine both the sedimentation and translational diffusion coefficients. The capillary tube is spun in a preparative centrifuge, removed, and placed in a light-scattering photometer equipped with a scanning mechanism. The intensity distribution of scattered light along the tube represents the concentration profile in the tube and provides the measure of boundary migration. The sedimentation coefficient is determined from this measure and the applied centrifugal field. The diffusion coefficient is obtained from a time-autocorrelation analysis of fluctuations in intensity of light scattered from any fixed point of the profile. These coefficients were obtained for two monodisperse systems, R17 bacteriophage and 28s ribosomal rat liver RNA. The molecular weights obtained from ratios of these coefficients are in good agreement with literature values. In the sedimentation analysis, deviations from linearity between boundary displacement and applied field were found to be less than 1%. This precision confirms that the boundary is stable for the capillary geometry even in the absence of a preformed density gradient. The sedimentation coefficients of identical samples were also measured with the Spinco Model E analytical ultracentrifuge; results of the two methods agree to within 4%.As a consequence of the capillary tube geometry and light-scattering detection, sedimentation coefficients can be obtained from sample volumes of less than 100 μl. This detection techniques is thus far demonstrated to be at least an order of magnitude more sensitive than Schlieren optics, thereby useful when uv absorption is not applicable. For diffusion measurements there are also several inherent advantages. The diffusion coefficient is obtained from the identical sample, and scanning provides the capability to measure D from various parts of the sedimentation profiles and thereby directly explore concentration dependence, homogeneity, and integrity of the sample. The capillary tube with a layer of silicone oil over the sample and centrifugation provides an effective method to cleanse the solution and trap all dust.
    Additional Material: 5 Ill.
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  • 2
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Semi-interpenetrating polymer networks based on polystyrene and polystyrene-polyisoprene three-block copolymers (SIS) were prepared by anionic polymerization. Factors affecting synthesis, such as composition, molecular weight of either the unattached SIS or the polystyrene between crosslinks, elastomer content, have been varied. Their effect on network formation was examined by extraction experiments and swelling measurements. Their morphology was investigated by means of electron microscopy.
    Additional Material: 3 Ill.
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  • 3
    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: Dihydroxy(phthalocyanino)germanium (1b) and Dihydroxy(tetraphenylporphino)germanium (3b) react with different monovalent alcohols to afford low-molecular bisalkoxyderivatives (1c-f and 3c-h). With bivalent alcohols and phenols polymers of the structure 5 and 6 or 8a, 9a and 8b, 9b, resp., are obtained.Dichloro(phthalocyanino)germanium (1a) and Dichlor(tetraphenylporphino)germanium (3a) react also with phenol, resp. hydroquinone, to give low-molecular and polymeric phenoxy-derivatives. The reaction of 1b and 3b with mono- and dibasic carboxylic acids leads to the corresponding esters.Dehydration of 3b gives polymeric porphin 15.The IR-spectra of the prepared compounds are discussed and compared with the analogous complexes of hemiporphyrazingermanium.Thermogravimetric and semiconductive measurements (σ298K = 10-10 - 10-15Ω-1 cm-1) are described.
    Notes: Dihydroxyphthalocyaningermanium (1b) und Dihydroxytetraphenylporphingermanium (3b) werden mit verschiedenen einwertigen Alkoholen zu den niedermolekularen Bisalkoxy-Derivaten (1c-f bzw. 3c-h) umgesetzt. Mit zweiwertigen Alkoholen und Phenolen können Polymere der Struktur 5 und 6 bzw. 8a, 9a und 8b, 9b erhalten werden.Dichlorphthalocyaningermanium (1a) und Dichlortetraphenylporphingermanium (3a) reagieren mit Phenol bzw. Hydrochinon ebenfalls zu niedermolekularen und polymeren Phenoxy-Derivaten. Die Umsetzung von 1b und 3b mit ein- und zweibasischen Carbonsäuren führt zu den entsprechenden Estern.Durch Dehydratisierung von 3b kann das polymere Porphin 15 hergestellt werden.Die IR-Spektren der dargestellten Verbindungen werden im Vergleich zu den analogen Hemiporphyrazingermaniumkomplexen diskutiert. Thermogravimetrische und Halbleitermessungen (σ298 K = 10-10 - 10-15Ω-1 cm-1) werden beschrieben.
    Additional Material: 6 Tab.
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  • 4
    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: Dihydroxy(meso-tetraphenylporphino)tin (1b), dihydroxy(phthalocyanino)tin (1d), and dihydroxy(hemiporphyrazino)tin (1f) react with bivalent phenols to afford polymers of type B. With 1,2-ethanediol and 1b low molecular compound 3 is obtained, which eliminates 1,2-ethanediol to give poly[oxyethyleneoxy(meso-tetraphenylporphin)stannandiyl] (4). Dehydration of the dihydroxy compounds 1b, 1d, 1f leads to polymers of type C. The IR-spectra of the prepared compounds are discussed; thermogravimetric and semiconductive measurements (σ298K≈10-6-10-16Ω-1cm-1) are described and compared with the analogous complexes of germanium.
    Notes: Dihydroxy-meso-tetraphenylporphinzinn (1b), Dihydroxyphthalocyaninzinn (1d) und Dihydroxyhemiporphyrazinzinn (1f) reagieren mit zweiwertigen Phenolen zu Polymeren des Typs B. Aus Äthylenglykol und 1b läßt sich die niedermolekulare Verbindung 3 erhalten, die unter Äthylenglykolabspaltung Poly[oxyäthylenoxy(meso-tetraphenylporphin)stannandiyl] (4) ergibt.Durch Dehydratation der Dihydroxy-Verbindungen 1b, 1d, 1f lassen sich Polymere des Typs C synthetisieren.Die IR-Spektren der dargestellten Verbindungen werden diskutiert; thermogravimetrische und Halbleitermessungen (σ298K≈10-6-10-16Ω-1cm-1) werden beschrieben und mit den analogen Germaniumverbindungen verglichen.
    Additional Material: 4 Tab.
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 9 (1975), S. 611-621 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The influence of both imposed anodic potential in Ringer's solution and surface finish on the fatigue lives of annealed 316 type stainless steel and annealed pure titanium were measured and statistically compared to fatigue data run in air. The applied potentials in simulated extracellular fluid approximated conditions existing within the body while also producing the types of surface defects actually found on removed long time implants within the time interval of the accelerated R. R. Moore fatigue tests. Differentiating tests were run at single levels of applied cyclic stress well above the endurance limits.In Ringer's solution, the fatigue life of the 316 stainless steel decreased with increasing applied potential, and at +500 mV was significantly shorter than when run in air. At each condition, the 316 stainless steel was independent of initial surface finish. In contrast, the fatigue life of titanium improved rapidly with increasingly fine surface finishes. Furthermore, compared to air, the application of +500 mV in Ringer's solution improved the life of the rough surface finished material and markedly increased the number of cycles to failure for the electropolished specimens.
    Additional Material: 5 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1881-1891 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A terpolymer of butadiene-styrene-vinylpyridine has been crosslinked by addition of iron chloride. Differential enthalpic analysis gives evidence of a two-phase system. Electron microscope studies at 0.1 and 1 MeV show the existence of precipitates. The majority of these ironrich aggregates have diameters less than 100 Å. Their form is polyhedral but very nearly spherical. No crystallinity has been detected inside the clusters. Thus the existence of strong interactions as in crystals of FeCl3 hydrates is excluded.
    Additional Material: 8 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1057-1061 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 389-398 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The glass transition behavior of two sets of ABA poly(styrene-b-isoprene) block copolymers was examined by differential scanning calorimetry. In one series, the triblock copolymers had different total molecular weights and the same (30 wt %) polyisoprene content, in the other, the molecular weight was constant (30,000 g/mol) and the elastomer content was the variable. For all triblock copolymers studied, the data show an inward shift for the glass transition temperatures Tg of the corresponding homopolymers. This shift increases for the rigid-phase Tg as the polystyrene block length decreases. Depending on their molecular characteristics, two, three, or only one Tg were found. The third Tg was interpreted in terms of the existence of an interphase. Some of these conclusions could be confirmed by transmission electron microscopy.
    Additional Material: 4 Ill.
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