GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Phase-separation dynamics of a ternary mixture coupled with reversible chemical reaction (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 1519-1529 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The phase-separation dynamics of a ternary mixture (A, B and C) coupled with a reversible chemical reaction between the two constituents A and B is presented. It is demonstrated that the free-energy functional form of time-dependent-Ginzburg-Landau equation describing the phase-separation dynamics of the ternary mixture coupled with a reversible chemical reaction is similar to that of the mixture composed of a block copolymer and a homopolymer. Our simulation study reveals that for the case of equal forward and backward reaction rates, the lamellar thickness scales with the reaction rate constant as a single power law λL∼Γ−0.22, regardless of high or low reaction rate regimes. This study sheds insight to the unique features of the involvement of chemical reaction in the phase separation of the ternary mixture. If chemical reaction and phase separation take place simultaneously, the different pattern evolutions at high and low reaction rate constants are originated from the balance between the domain coarsening due to phase separation and the breakup of the continuous phase due to the chemical conversion. The different pattern evolution at high and low reaction rate constants when chemical reaction lags behind phase separation can be interpreted in terms of the discrepancy between the domain sizes at the time step immediately before the turning on of the chemical reaction and the inherent lamellar thickness. It is also pointed out that the crossover of the ternary mixture from one phase region to another, due to the concentration change between A and B, might generate interesting steady-state domain patterns. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1425820
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The rheology and morphology of phase-separating fluids with viscosity contrast (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 7783-7792 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this paper, the effects of viscosity contrast between the components on the rheology and morphology of phase-separating binary fluids have been studied by numerically solving time-dependent Ginzburg–Landau equation and Navier–Stokes equation. It is found that, the viscosity contrast between the components strongly affects the bulk contribution to the overall rheological behavior. When the viscosity of the minor phase is higher, the trend of bulk contribution is contrary with that of interfacial contribution. Therefore, the non-Newtonian behavior is weakened. When the viscosity of the minor phases is lower, the evolution of bulk contribution is the same as interfacial contribution, and thus the non-Newtonian behavior is strengthened. However, the interfacial contribution still plays the crucial role in the overall rheological behavior. When the system contains two droplets or many domains, due to the merging of domains induced by shear flow, there is a decrease of interfacial volume fraction. Therefore, the interfacial contribution of rheology decreases and forms a peak at small shear strain. Correspondingly, the bulk contribution has also been altered. However, whether the bulk contribution increases or decreases will depend on the viscosity contrast. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1407294
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    The effect of shear flow on morphology and rheology of phase separating binary mixtures (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 8348-8361 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The morphology and the corresponding rheological properties of phase separating binary mixtures under shear flow are studied by computer simulation based on the modified time-dependent Ginzburg–Landau (TDGL) model. In order to investigate the hydrodynamic effect, model H in three dimensions has been used to simulate the phase separation of binary fluids under shear flow. For the sake of comparison, the simulation has also been performed based on simple binary solid model (model B). It is found that, for deep and critical quench, the domain grows faster and the domain anisotropy is lower in binary fluids due to the internal flow field induced by hydrodynamic interaction. For deep and off-critical quench, the internal flow field makes the elongated domain quickly relax to their original spherical shape before they are mutually contacted each other. Thus, it reduces the domain merging probability. It is also found that, for deep and critical quench, there are two peaks appeared in the shear viscosity as a function of shear strain at low shear rate, which agrees with the experimentally observations quite well. For shallow quenching, the broader interfaces suppress the internal flow caused by hydrodynamic interaction and thus the difference between binary solids and binary fluids is small. All these observed unique characters have been explained according to the hydrodynamic interaction and the relaxation rate of the deformed interface.© 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1313553
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Surface enrichment effect on the morphological transitions induced by directional quenching for binary mixtures (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 719-727 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The morphological transitions during directional quenching-induced spinodal decomposition in binary mixtures are investigated by computer simulation. By setting the quenching front between the stable and unstable phases, and shifting the front with a constant velocity, the evolution of the domain morphologies is examined numerically on the basis of the time-dependent Ginzburg–Landau (TDGL) equation. Three different types of morphologies are found for the critical quenching. One is irregular morphology (IM), which is essentially equivalent to that produced by homogeneous quenching. The other two are regular, representing the characteristics of the directional quenching process. One is regular lamellar morphology (RLM) and the other is regular column morphology (RCM). By varying the shifting velocity of the cooling front, two morphological transition velocities, va from IM to RLM, and vi from RLM to RCM, are observed. In contrast to that, for the case of off-critical quenching, a new transition velocity vb from RCM back to RLM can be found if the cooling front is further shifted slower. This characteristic morphological transition is attributed to the surface enrichment effect appearing in the nonequal volume fraction system, which competes with linear instability triggered by initial thermal fluctuation in the early stage of spinodal decomposition. Detailed studies reveal that RLM can be easily formed and thus the region of RCM is reduced when the surface enrichment effect is stronger. On the other hand, RCM will be preferred if the initial thermal fluctuation is stronger. The quantitative relation between lamella width and shifting velocity of the cooling front is also presented. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481847
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Monte Carlo simulation of self-avoiding lattice chains under slit flow (1999)
    Springer
    Rheologica acta 38 (1999), S. 562-568 
    Details
    ISSN: 1435-1528
    Keywords: Key words Slit flow ; Monte Carlo simulation ; Polymeric chain ; Bond fluctuation model ; Nonlinear rheological behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract This paper proposes a pseudo-potential describing slit flow in the formalism of lattice Monte Carlo simulation with the bond fluctuation algorithm as the unique basic micro-relaxation mode. The main characteristics of slit flow, such as the parabolic velocity profile and the pressure-flux relationship, are successfully reproduced in a three-dimensional self-avoiding multi-chain system. Both Newtonian and non-Newtonian regimes are revealed. The chain conformation and nonlinear rheological behavior are investigated. The simulation results agree with experimental measurements. This method can be used to investigate the viscoelastic properties at different layers as well as the global properties. Some peculiar phenomena in inhomogeneous flow are found to be consistent with previous theoretical predictions by others.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003970050208
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Monte Carlo simulation of kinetics and chain-length distribution in radical polymerization (1993)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Theory and Simulations 2 (1993), S. 747-760 
    Details
    ISSN: 1018-5054
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In this paper, the Monte Carlo method for numerically simulating the kinetics and chain-length distribution in radical polymerization is described. Because the Monte Carlo method is not subject to the assumption of steady-state, it is particularly suitable for studying the kinetic behaviour before the steady-state has been reached and for systems in which the steady-state assumption may be violated. Illustrative applications of the algorithm given in this paper not only demonstrate convincingly both the feasibility and usefulness of the algorithm, but also provide some new insight into the illustrative examples. For the case of pseudostationary radical polymerization such as rotating-sector and pulsed-laser initiations, we have found that the pseudostationary radical concentration can be reached after two or three initiation periods. However, the number-average chain-length x̄n reaches the pseudostationary value much slower than the radical concentration. It is oscillatively reaching the pseudostationary value, and the amplitudes of the oscillations are decreasing with time. We have also found that the chain-length distribution of the resulting polymer in the case of pseudostationary radical polymerization with termination by combination has stronger periodic modulation. Hence, it should be easier to locate the points of inflection in practice. Therefore, the rate constant of propagation, kp, can be determined precisely for systems which are dominated by a combination-type of termination.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mats.1993.040020511
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Polarized optical microscopy and small-angle light-scattering studies on nematic droplets in PDLC electro-optical materials (1994)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 5 (1994), S. 603-605 
    Details
    ISSN: 1042-7147
    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
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1994.220050924
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Morphology of fibers formed via thermally induced phase separation of polypropylene and liquid paraffin blend in stress-field (1999)
    Springer
    Polymer bulletin 43 (1999), S. 291-296 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Phase diagram obtained from small angle light scattering (SALS) and differential scanning calorimetry (DSC) of polypropylene/liquid paraffin blend system indicates that the melts undergo solid-liquid phase separation upon cooling and liquid paraffin is expelled out of crystalline region of polypropylene. Fibers spun under high take-up draw ratio are found to be hard-elastic. Long periods in the meridional direction are observed on the curves of small angle X-ray scattering (SAXS), and the yield point of fibers decreases with the increase in liquid paraffin content, which indicates such fibers have row-nucleated lamellar structure perpendicular to the fiber direction. The feasibility of preparing microporous membranes by stretching such fibers is investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002890050565
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    A preliminary morphological evidence for the existence of back-flow effect associated with the formation of band texture after cessation of shear for a polymeric liquid crystal (1996)
    Springer
    Polymer bulletin 36 (1996), S. 773-778 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The band texture of the hydroxypropylcellulose (HPC) film is observed after cessation of shear by optical microscopy and scanning electron microscopy (SEM). The sinusoidal supramolecular structure associated with the band texture of HPC is verified by polarized optical microscopy, so the band texture corresponds to the spatial periodicity of local director or molecular orientation. On the other hand, however, the pleated morphology, a depth periodicity, is confirmed by SEM and the pleat period is consistent with the band period. What is more, even without polarizer and analyser, the bands can still be found in an optical microscope with the same periodicity as those under cross polars, and these bands might be attributed to a density periodicity. Both the depth and density periodicities result from the mass flow after cessation of shear and must be coupled to the orientation periodicity resulting from director rotation. As a consequence, we propose that the back-flow effect is striking in the formation of band textures and should be taken into consideration in order to give a plausible and explicit mechanism of band formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00338643
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Band-texture decorated spatial distribution of molecular orientation around air bubbles in hydroxypropyl cellulose aqueous solution (1996)
    Springer
    Polymer bulletin 37 (1996), S. 245-251 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The air bubbles in the concentrated hydroxypropyl cellulose (HPC) aqueous solution have been employed to monitor the spatial distribution of molecular orientation around spherical or ellipsoidal particles within the liquid crystalline matrix. The deformation of the air bubbles under shear flow was observed in a polarizing microscope. The stream lines are curved near air bubbles. Corresponding spatial distribution of the molecular orientation was revealed by the technique of band-texture decoration. Associated pleated morphology was also observed in a scanning electron microscope.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00294128
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...