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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 651-668 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two series of polyurethane zwitterionomers based on 4,4′-methylene-di(phenyl isocyanate) (MDI), N-methyl diethanolamine (MDEA)Systematic IUPAC name: 2,2′-(methylimino)diethanol., and either 1350 molecular weight hydroxyl terminated polybutadiene or 1000 molecular weight poly(tetramethylene oxide)Systematic IUPAC name: poly(oxytetramethylene). were synthesized. Zwitterionization was accomplished by quaternizing the tertiary amine of MDEA with 1,3-pro-panesultone. In Both series, IR analysis suggests that the sulfonate ion SO3- associates with the counter ion on the chain extender and the acidic hydrogen of the urethane linkage. Ammonium sulfonation shifts the soft segment Tg of polyether-based material to lower temperatures suggesting that ionization improves microphase separation. The soft segment Tg of the polybutadiene system is unaffected by ionization. IR dichroism measurements show that with increasing ammonium sulfonation both the hard and soft segments in the polyether-polyurethane zwitterionomers orient to a greater extent with deformation. In contrast, in the poly-butadiene-based zwitterionomers the orientability of the hard segment decreased with ionization while the soft segment showed significant chain alignment. Coupling the dichroism measurements to stress-strain results suggests that the hard segment domains of the polyether-polyurethane system possess more of an interconnected structure, while the polybutadiene-poly-urethane system contains hard segment domains which are largely isolated. The formation of different morphologies in the two systems of zwitterionomers may be due to the different interdomain surface tensions.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 185 (1984), S. 2429-2435 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Small angle neutron scattering experiments were performed on a blend of deuterated and protonated hydroxyl terminated oligo(oxytetramethylene)s. The oligomer had a number-average molecular weight of 1000. The experimental data were fitted to a Debye function in order to obtain the radius of gyration of the chains. The measured radius of gyration, which was corrected for molecular weight distribution, was found to compare well with the values reported in the literature for poly(oxytetramethylene) in a theta solvent, as measured by viscosity methods and extrapolated to a molecular weight of 1000. Thus, this short oligomeric species has a random coil configuration. The weight-average molecular weight determined from the SANS data was 1540, compared with a value of 1450 determined from high performance liquid chromatography. This implies that no isotopic segregation of the deuterated and protonated species occurs.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 10 (1966), S. 1837-1844 
    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 viscoelastic properties of some polyester-urethanes are compared with the properties of other polymers. The behavior observed is anomalous in that these polyurethanes exhibit an unusually high value of modulus well above their Tg, unaccounted for by either crosslinking or crystallinity. Various experiments including incorporation of plasticizes of widely varying chemical composition have suggested interpretation of the system as a block copolymer, each block having its own Tg. Each of the two types of blocks seems to associate with similar blocks from other molecules.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 3035-3061 
    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 compatibility, morphology, and mechanical properties of poly-∊-caprolactone (PCL) blended with poly(vinyl chloride), nitrocellulose, and cellulose acetate butyrate are described in this study. Methods used in this investigation included differential scanning calorimetry, dynamic mechanical testing, small-angle light scattering, light microscopy and stress-strain testing. Blends of PCL with poly(vinyl chloride) (PVC) are shown to be compatible in all proportions. In the PCL concentration range 40-100%, the PCL crystallizes in the form of negative spherulites. The spherulites were found to be volume filling with as much as 35% PVC. The nitrocellulose blends with PCL exhibited the glass transition behavior of a compatible system over the composition range of 50-100% PCL. At lower PCL concentrations, phase separation was apparent. The PCL crystallinity was present only in the nitrocellulose blends with more than 50% PCL, and it was in the form of rod-like super-structures. Blends of PCL with cellulose acetate butyrate were shown to be phase separated, with one phase having nearly equal proportions of the two polymers. The PCL crystallinity was in the form of negative spherulites and was formed with PCL compositions as low as 50%. Stress-strain results show polycaprolactone to be an effective plasticizer for poly(vinyl chloride) and the cellulose derivatives studied.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 201-214 
    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 diffusivities of simple gases through a series of polyurethane block copolymers of differing aromatic urethane content and type of soft segment were measured using a quadrapole mass spectrometer as a detecting device. Although an Arrhenius expression generally described the temperature dependence of diffusion in this system, a discontinuity was observed in the Arrhenius plots for some materials, and the discontinuity was found to be related to the onset of the glass transition in the hard domains. Increasing the hard segment content of the materials decreased the diffusivity due to the increase in the activation energy of diffusion. Increasing the soft segment length brought about a decrease in the activation energy with an increase in diffusivity. Polyster urethanes had lower activation energies for diffusion than polyether urethanes of similar hard segment composition. Finally, as the penetrant diameter was increased, a decrease in the diffusivity and an increase in the activation energy was noted.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 2989-3006 
    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 objective of this research was to study the morphology and properties of PVC-polyurethane blends. Studies on blends of a segmented polyether polyurethane with PVC were carried out utilizing differential scanning calorimetry, Rheovibron, stress-strain, infrared peak position studies, and infrared dichroism experiments. This thermodynamically incompatible system was made kinetically compatible by precipitation from tetrahydrofuran (THF) solutions. THF-dioxane solution casting and melt processing produced an incompatible system. The compatible polyurethane-PVC system contains a well-mixed PVC-polyether matrix phase as evidenced by Tg shifts, orientation characteristics, and infrared peak position changes. The aromatic urethane segments which exhibit microphase separation in the pure polyurethane are not solubilized by blending with PVC by any of sample preparation methods used in this study.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2160-2174 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A methodology and analysis is presented to quantitatively characterize bacterial attachment and detachment kinetics on biomaterial surfaces in a laminar flow field as a function of shear stress. The spatial distribution of adherent bacteria on the surface of a radial-flow chamber is monitored via automated videomicroscopy with motorized three-axis stage and focus control, allowing rapid automated measurement of the attached cell density as a function of time and radial position. Intrinsic rate constants for attachment and detachment are defined and estimated by fitting mathematical models to the resulting data. The model for cell attachment accounts for the global transport of cell in the chamber to estimate the cells concentration near the collector surface. The model for cell detachment accounts for heterogeneity in the adhesion energy of the attached cell population. These models yield first-order attachment and detachment rate constants that intrinsically reflect the probabilities of bacteria attachment and detachment as a function of applied shear stress, depending on only the local interactions between the cell and the surface. The validity of each model was tested by statistical analyses of the goodness-of-fit to data that resulted from a study comparing adhesion of Staphylococcus aureus to three different polymeric surfaces of Varying surface properties and adhesive protein coatings.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 26 (1988), S. 953-966 
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The multiple endothermic behavior of poly(tetramethylene terephthalate) (PTMT) and its random and block copolymers with poly(tetramethylene isophthalate) (PTMI) and poly(tetramethylene oxide) (PTMO) is described. The differential scanning calorimetry heating scans of these polymers exhibit up to four endotherms. Endotherm I, the lowest-temperature endotherm, is an annealing peak and is ascribed to a clustering of PTMT sequences. Endotherms II, III, and IV are associated with crystal populations originated during periods of isothermal crystallization, cooling, and heating, respectively. The dependence of the endotherms on sample composition, crystallization and annealing temperatures, crystallization and annealing times, and sample cooling and heating rate is discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 1163-1177 
    ISSN: 0887-6266
    Keywords: nuclear magnetic resonance (NMR) of MDI-based polyurethanes ; polyurethanes, MDI-based, solid-state NMR of ; chain motion and microphases in segmented polyurethanes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 13C solid-state nuclear magnetic resonance (NMR) experiments on linear polyurethanes and poly(ether-urethane) block copolymers demonstrate that 13C spin-lattice relaxation experiments in the laboratory [T1(C)] and rotating [T1p(C)] frames provide the most information about domain morphology in these microphase-separated polymer systems. T1(H) TCH, and T1p(H) data are less useful in a 4,4′-methylene bis(p-phenyl isocyanate)-1,4-butanediol (MDI/BD) hard-segment material, the MDI bridging methylene and the MDI urethane carbonyl T1(C and T1p(C) times fall in characteristic ranges for crystalline, amorphous, interfacial, and dissolved species. BD methylene carbons have short T1p(C) for crystalline and long T1p(C) for amorphous hard-segment aggregates. The distinct T1p(C) and T1(C) fractins observed are attributed to the presence of several crystalline polymorphs. Both T1(C) results and DSC endotherms indicate that the crystalline polymorphs present in the poly(ether-urethane) are less ordered than the types seen in the pure hard-segment material. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 581-588 
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polyurethanes based on methylene bis(p-phenyl isocyanate), bis(hydroxymethyl) propanoic acid, and poly (tetramethylene oxide) were synthesized, and their morphology and physical properties investigated. The acid polyurethanes exhibited very poor phase separation and mechanical properties, but upon neutralization with alkali metals phase separation improved dramatically and the materials resembled tough elastomers. The choice of cation played a much less important role than hard segment content in determining morphology and properties. Small-angle x-ray scattering patterns of these ionic polyrethanes exhibit two peaks, one characteristic of scattering between the hard and soft domains and the other reflecting scattering from aggregates of ionic groups residing within the hard domains. While ionic aggregation is the primary driving force for phase separation in these materials, their morphology more closely resembles that for nonionic polyurethanes than that for conventional ionomers, because the ionic groups exist in blocks composed primarily of rigid diisocyanate residues.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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