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  • Polymer and Materials Science  (23)
  • Electrogastrography  (7)
  • Electrogastrogram  (3)
  • 11
    Electronic Resource
    Electronic Resource
    Frequency components of the electrogastrogram and their correlations with gastrointestinal contractions in humans (1993)
    Springer
    Medical & biological engineering & computing 31 (1993), S. 60-67 
    Details
    ISSN: 1741-0444
    Keywords: Electrogastrogram ; Electrogastrography ; Gastric motility ; Intestinal motility ; Myoelectrical activity ; Spectral analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02446895
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  • 12
    Electronic Resource
    Electronic Resource
    Hydrogen bonding in polymer mixtures (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 24 (1986), S. 1597-1609 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The enthalpy-infrared frequency shift correlation for simple acids and bases is extended to study hydrogen bonding in polymer systems. The acidity of a polymer is calibrated by comparing the shifts in hydroxyl absorption frequency of the acidic polymer when mixed with a series of bases with the corresponding spectral shifts of known acids with the same bases. The basicity of a polymer is calibrated by measuring the hydroxyl frequency shifts of known acids when mixed with the basic polymer. For polymers containing carbonyl groups, the shift in carbonyl absorption is also a measure of basicity. The acidity and basicity constants obtained for polymers are in good agreement with the values for small-molecule analogs. The enthalpies of hydrogen bond formation in polymer mixtures are calculated from the acidity or basicity constants.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1986.090240716
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  • 13
    Electronic Resource
    Electronic Resource
    Study of the dielectric properties of ferroelectric liquid crystals and related side chain liquid crystalline polymers (1995)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 196 (1995), S. 2601-2614 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Broadband dielectric spectroscopy (frequency range 10-1-106 Hz) was used to analyze the frequency and temperature dependence of the molecular dynamics of a series of ferroelectric liquid crystals (FLCs) and polymers which exhibit a chiral smectic C (SC*) phase in a wide temperature range (about 190°C) including room temperature. Two ferroelectric modes, Goldstone and Soft mode, were observed in the low-molar-mass FLCs. Both of these modes were found in the SC* phase; however, only the soft mode was present in the smectic A (SA) phase. On the other hand, two collective relaxation processes (Soft and Goldstone mode) and four molecular relaxations (δ, α, β and γ-relaxation) of the side chain liquid crystalline polymer were demonstrated.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1995.021960813
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  • 14
    Electronic Resource
    Electronic Resource
    Ultrasonic devulcanization of rubber vulcanizates. I. Process model (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 59 (1996), S. 803-813 
    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: Tire and rubber waste recycling is an important issue facing the rubber industry. In addressing this issue, the present article describes the first attempt to formulate a model and to simulate a novel continuous ultrasonic devulcanization process. The proposed model is based upon a mechanism of rubber network breakup caused by cavitation, which is created by high-intensity ultrasonic waves in the presence of pressure and heat. Dynamics of bubble behavior is described by the Notlingk-Neppiras equation with incorporation of an additional term based upon elastic strain-energy potential. Acoustic pressure arising in the ultrasonic field is related to void formation. Their concentration is calculated based upon nucleation and growth of gas bubbles in crosslinked elastomers under negative driving pressure. The breakup of a three-dimensional network in crosslinked rubbers is combined with flow modeling. The viscosity function required for this modeling is based upon a power-law model which includes temperature, shear rate, and gel fraction dependence. © 1996 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Ultrasonic devulcanization of rubber vulcanizates. II. Simulation and experiment (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 59 (1996), S. 815-824 
    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 simulation results based on the devulcanization model presented in Part I of this study are described for devulcanization of SBR vulcanizates. The vulcanizates are conveyed by a single-screw extruder to a thin gap between a stationary die and a vibrating horn. Gapwise velocity, temperature, and shear-rate distributions along the die length are calculated. Predictions of the model for changes of various structural characteristics including gel fraction, fraction of various broken bonds, rate of their breakup, and void formation along die length are given. Devulcanization energy consumption and energy dissipated by ultrasonic waves are calculated. Comparison of these energies indicates that the devulcanization energy represents only a small fraction of the dissipated energy. The predicted results for gel fraction, crosslink density, die characteristics, and “mixing cup” temperature are compared with the experimental data. These predicted results are found to be only in qualitative agreement with experimental observations. The theoretical and experimental results indicate that the rubber is partially devulcanized and the devulcanization process is accompanied by some degradation of the macromolecular chains. © 1996 John Wiley & Sons, Inc.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Preparation of gradient-index (GRIN) polymer fibers for imaging applications (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 1379-1383 
    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: A closed extrusion process combined with a core-shell separation die design is developed in this study for preparing gradient index (GRIN) polymer fibers with a quadratic distribution of the refractive index. The material system used in this investigation is methyl methacrylate (MMA, n = 1.49) and benzyl methacrylate (BzMA, n = 1.568). The refractive index differences between the center and the periphery (Δn) of the prepared polymer fibers increase from 0.0115 to 0.020 when BzMA in the reactant mixtures increases from 17 to 28%. This finding would suggest that increasing the high refractive index monomer in the reactant mixture increased Δn. The Δn values decrease from 0.018 to 0.0135 when the diffusion zone temperature increases from 70 to 90°C. The diffusion rates of the monomers increase with the temperature, thereby causing BzMA and MMA to distribute more uniformly at a higher temperature than at a lower one. This uniform distribution leads to the decrease of Δn with an increasing temperature. The prepared GRIN polymer fibers have potential applications as imaging lenses for scanners, fax machines, and copiers. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Phase separation of poly(ether sulfone imide) modified epoxy resin (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 61 (1996), S. 2423-2435 
    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: Poly(ether sulfone imide)s (PEI) with molecular weight Mn ∼ 104 were synthesized from 3,3′,4,4′-benzophenone tetracarboxylic dianhydride and amine terminated poly(ether sulfone) having molecular weights ranging from Mn ∼ 400 to Mn ∼ 4000. Thus, the PEIs had the same molecular weight but various imide and ether sulfone contents. The PEIs were mixed with a stoichiometric mixture of diglycidyl ether bis-phenol-A (DGEBA)/diamino diphenyl sulfone (DDS). The effect of PEI on the curing reaction of DGEBA/DDS and the morphology of the polymer blend were studied by differential scanning calorimetry (DSC) and optical microscopy. In the DGEBA/DDS/PEI blend with a fixed PEI molecular weight and PEI concentration but with various imide content, the experimental data revealed the PEI with a higher content of ether sulfone had a lower Tg and a better compatibility with solvents and epoxy resins; the curing reaction rate of DGEBA/DDS/PEI was faster for PEI with a higher imide content; the DSC data of cured DGEBA/DDS/PEI showed two Tgs, indicating phase separation between PEI and cured epoxy resins; and the data of optical microscopy showed that the compatibility of PEI with epoxy resins increased with the content of ether sulfone in PEI. © 1996 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Effects of solvent treatment on crystallization kinetics of poly(p-phenylene sulfide) (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 1985-1993 
    Details
    ISSN: 0887-6266
    Keywords: poly(phenylene sulfide) ; crystallization kinetics ; multiple melting ; solvent effect ; differential scanning calorimetry ; primary and secondary crystallization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Isothermal melt crystallization kinetics were investigated by differential scanning calorimetry (DSC) for virgin and α-chloronaphthalene solvent-treated poly(phenylene sulfide) (PPS) systems. The overall crystallization rates were found to be much faster for the solvent-treated PPS than for the virgin neat PPS. Additionally, the Avrami crystallization plot for the solvent-treated PPS samples appeared as two straight portions with an apparent discontinuity, but as a continuous straight line for the virgin PPS system. After the treatment of solvent dissolution and subsequent drying, the residual trace α-chloronaphthalene, upon being quenched to the crystallization temperatures, initiated some localized solvent-induced nuclei-like crystals in PPS. It was the nuclei that enhanced secondary crystallization in treated PPS during the second stage, and the higher extents of secondary crystallization in the solvent-treated PPS caused the apparent discontinuous break in the Avrami plots. The causes for the difference were explained and the mechanism of the sequential primary/secondary crystallization kinetics for the solvent-treated PPS was satisfactorily described with a proposed series-parallel crystallization model. ©1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090331401
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  • 19
    Electronic Resource
    Electronic Resource
    Depolymerization of poly(ethylene terephthalate) resin under pressure (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 1501-1507 
    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 process of depolymerization of PET resin by EG glycolysis under pressure is investigated. The kinetics of this pressurized depolymerization of PET resin is discussed. It was found that the rate of depolymerization is dependent of temperature, pressure, and concentration ratio of EG to PET. The rate of depolymerization is proportional to the square of EG concentration and faster than that under atmospheric pressure. Glycolyzed products under pressure consist of the PET monomer, BHET, and oligomers, mostly dimer and trimer. An equilibrium between BHET and oligomers is attained quickly soon after the depolymerization step is completed in the case of a higher ratio of EG/PET used. In the case of lower ratio of EG/PET, the final product now consists of higher molecular weight of oligomers rather than monomer, dimer, and trimer.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420603
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  • 20
    Electronic Resource
    Electronic Resource
    Low loss second-order nonlinear optical polymers based on all organic sol-gel materials (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 55 (1995), S. 209-214 
    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: A new class of all organic sol-gel second-order nonlinear optical (NLO) materials based on hexa(methoxymethyl) melamine (HMM) was developed. Two NLO active chromophores, 4 (4′-nitrophenylazo) aniline (DO3) and 4-amino-4′-nitrobiphenyl (ANB), were incorporated into the melamine matrices. The samples exhibited second-order optical nonlinearity after poling and curing at 220°C for 30 min. DO3/HMM and ANB/HMM samples showed a second harmonic coefficient, d33 of 10.7 and 1.8 pm/V at 1064 nm, respectively. The temporal stability of both systems was studied at room temperature as well as at 100°C. Waveguide optical losses of samples at 633 and 830 nm were found. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070550203
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