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  • 11
    Electronic Resource
    Electronic Resource
    Effects of ammonia/ammonium thiocyanate on cotton fabric (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2025-2032 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of ammonia/ammonium thiocyanate (NH3/NH4SCN) treatment of the swelling behavior, structural changes, and physical properties of cotton sheeting was compared with that of sodium hydroxide and liquid ammonia mercerization. Increased percent shrinkage, accessibility to a large dye molecule, dyestuff absorption, swelling with water, and water imbibition showed that NH3/NH4SCN had improved the accessibility of the cotton fabric. X-ray diffractograms showed the characteristic Cellulose I crystal lattice. X-ray diffraction and infrared absorption spectroscopy indicated that the crystallite size was unchanged and the swelling from the NH3/NH4SCN treatment occurred in the amorphous regions of the cellulose since the observed crystal structure was unchanged. Moisture regain determinations and barium hydroxide absorption suggested that some recrystallization of the cellulose may have occurred from the NH3/NH4SCN treatment. Fibers treated with NH3/NH4SCN showed a cross sectional shape similar to that of the origianl fibers but with reduced lumen area.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1987.080250801
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  • 12
    Electronic Resource
    Electronic Resource
    An experimental investigation on the evolution of the molecular weight distribution in styrene emulsion polymerization (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 989-1006 
    Details
    ISSN: 0887-624X
    Keywords: emulsion polymerization ; molecular weight distribution ; styrene ; morphology ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Styrene ab initio emulsion polymerizations were conducted at 70°C in an automated reaction calorimeter. Two polymerizations were performed, one above and the other below the critical micelle concentration (CMC) of the surfactant, thus ensuring differing polymerization kinetics between the two: the system below the CMC gave large particles that were expected to follow pseudobulk kinetics, while that above the CMC gave small particles that were expected to follow zero-one kinetics. The evolutions of the molecular weight distributions (MWDs) were characterized by removing samples periodically during the course of the reactions and analyzing with gel permeation chromatography. Interpretation of the data used average molecular weights, the GPC MWDs, and the number MWDs, as functions of conversion. It was found that all of the number MWDs (plotted as ln (number of polymer chains) vs. molecular weight of polymer chains) were concave-up at low molecular weights and become nearly linear at molecular weights (≥3-4 × 106); this linearity is expected from theory. The slope of the high molecular weight region was consistent with theory for the dominant mode for chain stoppage: termination and transfer for the pseudobulk system and (predominantly) chain transfer to monomer for the zero-one system. The most likely explanation for the concavity of the number MWDs is a heterogeneity of radicals: some surface anchored with sulfate end groups and others (with hydrogen end groups arising from transfer to monomer and/or reentry) being more mobile. Thus, two types of termination are proposed: slow reaction-diffusion for the less mobile surface anchored chains, and rapid short-long (center of mass) termination for the more mobile hydrogen-terminated chains. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 989-1006, 1997
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Detection of DNA hybridization using self-assembled bilayer lipid membranes (BLMs) (1997)
    Weinheim : Wiley-Blackwell
    Electroanalysis 9 (1997), S. 1067-1071 
    Details
    ISSN: 1040-0397
    Keywords: Electrochemistry ; Biosensor ; Self-assembled bilayer lipid membranes ; Nucleic acid hybridization ; Transduction ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The present work reports the use of self assembled bilayer lipid membranes supported on the surface of a metal (s-BLMs) as transducers for the direct electrochemical monitoring of DNA hybridization. Characterized oligomers based on single stranded deoxyribonucleic acid (ssDNA) thymidylic acid icosanucleotides that were terminated with C16 (dT20-C16) and deoxyadenylic acid icosanucleotides (dA20) were used for the hybridization procedure at the lipid membrane surface. The decrease of the ion conductivity observed during the hybridization procedure is indicative of the formation of the duplex, which may subsequently be excluded from the membrane. The incorporation of nucleic acids into the lipid matrix was investigated by differential scanning calorimetric (DSC) experiments. The present simple electrochemical biosensor for monitoring of DNA hybridization was regenerable for multiple cycles of application. This approach provides low detection limits for DNA (a few hundreds of fmol), fast response times (on the order of a few minutes), mild conditions of hybridization and capability of analyzing small volumes of sample.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140091407
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  • 14
    Electronic Resource
    Electronic Resource
    Kinetics of formation of fibrin oligomers. I. Theory (1982)
    New York : Wiley-Blackwell
    Biopolymers 21 (1982), S. 2253-2264 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The course of formation of fibrin oligomers is treated theoretically for the condition that self-assembly of fibrin monomers is rapid compared with the loss of A peptides by the enzymatic action of thrombin. The rate constant for removal of the second A peptide is taken to be larger than that for the first by an arbitrary factor q; the association of activated A sites with their complementary a sites is assumed to be random and independent of oligomer size. Two types of oligomers are considered: noncovalently bonded protofibrils formed by the staggered overlap of thrombin-activated monomers and covalently bonded linear oligomers formed by factor XIIIa-mediated end-to-end ligation of adjacent monomers within protofibrils. Oligomers of the first type, if ligated, are dissociated to oligomers of the second type by solubilization in SDS-urea. Theoretical curves are presented for xw and x′w (weight-average degree of polymerization of staggered overlap and linear ligated oligomers, respectively) and for the weight fractions of monomer, dimer, and decamer of both ligated and unligated species as functions of y, the fraction of A peptide removed; and also for wx and w′x, the weight fractions of x-mer of the respective oligomer types, as a function of x at y = 0.5. With increasing q, the maximum wx or w′x that a low oligomer will reach during the reaction decreases and the size distribution is broadened toward larger oligomers. Comparison with experiment is made in a companion paper.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360211112
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  • 15
    Electronic Resource
    Electronic Resource
    Polymerization of fibrin: Analysis of light-scattering data and relation to a peptide release (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 2017-2019 
    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.360220902
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  • 16
    Electronic Resource
    Electronic Resource
    Characteristics and design procedure of hyperbolic dies (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 30 (1992), S. 557-561 
    Details
    ISSN: 0887-6266
    Keywords: extrusion from hyperbolic dies, characteristics and design procedures in ; strain rate in extrusion procedures, hyperbolic die design and ; filament production with constant extensional strain rate with hyperbolic dies ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Nozzle profiles capable of generating constant extensional strain rates are termed hyperbolic dies. When used in polymer extrusion, they exhibit greater potential in inducing and retaining polymer molecular orientation than conventional capillary dies. Most mathematical expressions found in the literature involve several processing variables in describing and designing such nozzle profiles. This report reveals that a hyperbolic die profile, although rather complicated, can be expressed with equations in terms of two ordinary geometrical parameters - the exit diameter and the hyperbolic length. This finding greatly simplifies the design procedure of hyperbolic dies. The extensional strain rate of a hyperbolic die can be related to the length-to-diameter ratio for any given exit diameter. Examples of various types of die profiles are presented and their constant extensional strain-rate characteristics are discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1992.090300606
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  • 17
    Electronic Resource
    Electronic Resource
    Modeling of substrate-induced anisotropy in through-plane thermal behavior of polymeric thin films (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 1591-1596 
    Details
    ISSN: 0887-6266
    Keywords: anisotropy ; polymeric thin film ; coefficient of thermal expansion (CTE) ; Poisson's ratio ; through-plane direction ; finite element modeling ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymeric thin films are widely used in microelectronic applications for a variety of purposes. These films may possess completely isotropic material properties and yet still exhibit anisotropic effects due to the constraining influence of the substrate coupling into the film behavior via the film Poisson ratio. A theoretical model of this effect on the through-plane thermal properties of isotropic thin films for single layer (thin film rigidly clamped) and bilayer (thin film on substrate, e.g., silicon wafer) has been developed based on the assumption that the material follows Hooke's law in all directions. Finite element analyses using ANSYS 5.0A have also been performed to confirm theoretical results both for single-layer and bilayer models. In the case of Poisson ratio of 0.5, the effective coefficient of thermal expansion (CTE) in the thickness direction can be as high as three times that of the unconstrained film. © 1996 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Oriented noncrystalline structure in PET fibers prepared with threadline modification process (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 2035-2047 
    Details
    ISSN: 0887-6266
    Keywords: poly(ethylene terephthalate) ; controlled threadline dynamics ; orientation ; oriented noncrystalline phase ; fiber properties ; crystallinity ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The development of an oriented noncrystalline phase in a semicrystalline polymer filament has been studied via X-ray scattering. These unique PET fibers contain a relatively high noncrystalline content and also have high tenacity, high modulus, and low breaking elongation. Fiber properties were found to be very responsive to the oriented amorphous phase content. This phase was utilized for interpreting noncrystalline orientation in PET fibers produced by a new extrusion technique. Here, the oriented noncrystalline regions in a series of PET fibers varies from 6% to 63%, depending strongly on the production conditions. In particular, samples produced with a newly developed threadline modification process possess a high content of oriented noncrystalline polymer. Measurements such as dynamic and static mechanical properties have been performed on various samples, and these properties are related to the oriented noncrystalline phase. The results provide direct evidence for the existence of highly oriented noncrystalline material in these unique PET fibers spun with a threadline modification process. © 1996 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Network parameters and scaling behaviour of chemically crosslinked hydrogels of poly[(N,N-dimethylacrylamide)-co-(methyl methacrylate)] (1997)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 198 (1997), S. 1885-1892 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Copolymerization of N,N-dimethylacrylamide (DMA) with methyl methacrylate in both the presence and absence of ethylene dimethacrylate (EDMA) was effected to very high conversion by γ-irradiation. The resultant xerogels were swollen to equilibrium in water at five specific temperatures within the interval 280.2-338.2 K. The volume fractions of the polymer φ2 in the hydrogels were determined from the measured dimensions, and compression-strain measurements yielded the polymer-water interaction parameter, the effective crosslinking densities, and Young's moduli Y. The observed dependence of these parameters on copolymer composition and content of EDMA is discussed. A scaling law of the form Y ∝ φr2 is obeyed well by hydrogels of xerogels containing 80 wt.-% DMA (r = 2.37 ± 0.10) and moderately well by hydrogels of xerogels with only 50 wt.-% DMA (r = 2.54 ± 0.10).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1997.021980617
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  • 20
    Electronic Resource
    Electronic Resource
    Unique crystalline structure and performance of poly(ethylene terephthalate) melt spun fibers (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 909-917 
    Details
    ISSN: 0887-6266
    Keywords: crystalline morphology ; extended chain ; poly(ethylene terephthalate) ; melt spinning ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Modification of the threadline dynamics has effected significant alternations in the structure and improvements in the properties of high-speed melt spun poly(ethylene terephthalate) (PET) fibers. Key process parameters extant in the threadline dynamics, such as temperature, tensile stress, and deformation time, were independently controlled through proper implementation of on-line perturbations. The placement of a liquid isothermal bath in close proximity to the spinneret in the melt spinning threadline provided tremendous increase in the spinning stress while at the same time controlled the filament temperature corresponding to development of the desired fiber structure. Characterization of the fiber structure and physical properties has been carried out using birefringence measurements, density, shrinkage, x-ray diffraction, DSC, FTIR spectroscopy, and tensile tests. The results provided sufficient evidence to support the existence of a unique crystalline morphology that led to the significantly improved tensile properties and excellent dimensional stability of the resulting fibers. This unique crystalline morphology was typically characterized by the presence of a larger amount of extended chain segments and an enhanced molecular connectivity. ©1995 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090330606
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