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Liquids more advanced theories

In this chapter, we first describe the stmcture of networks, followed by the discussion of the simple classical models of elasticity and the more advanced theories such as the constraint and the tube models. We also give the molecular interpretation of coefficients obtained from the phenomenological theories. Some simulations relevant to mbberlike elasticity are then described, followed by a discussion of responsive gels because of their increasing interest to many groups. We then discuss the thermoelastic (force-temperature) behavior of networks, followed by the information on multimodal networks, liquid-crystalline (LG) elastomers, novel reinforcing fillers, and characterization methods. [Pg.182]

There are numerous more advanced theories of transport coefficients in liquids, mostly based on nonequilibrium classical statistical mechanics. Some are based on approximate representations of the time-dependent reduced distribution function and others are based on the analysis of time correlation functions, which are ensemble averages of the product of a quantity evaluated at time 0 and the same quantity or a different quantity evaluated at time t For example, the self-diffusion coefficient of a monatomic liquid is given by " ... [Pg.1193]

I have tried to remain true to my original brief, and produce a readable text for the more advanced consumer of molecular structure theory. The companion book Chemical Modelling from Atoms to Liquids (John Wiley Sons Ltd, Chichester, 1999) is more suitable for beginners. [Pg.353]

It seems probable that a fruitful approach to a simplified, general description of gas-liquid-particle operation can be based upon the film (or boundary-resistance) theory of transport processes in combination with theories of backmixing or axial diffusion. Most previously described models of gas-liquid-particle operation are of this type, and practically all experimental data reported in the literature are correlated in terms of such conventional chemical engineering concepts. In view of the so far rather limited success of more advanced concepts (such as those based on turbulence theory) for even the description of single-phase and two-phase chemical engineering systems, it appears unlikely that they should, in the near future, become of great practical importance in the description of the considerably more complex three-phase systems that are the subject of the present review. [Pg.81]

The kinetic theory of gases is far more advanced than that of liquids partly because of complex interactions among the molecules of liquids. We may estimate the viscosity of a pure liquid from the following relation based on the Eyring rate theory ... [Pg.63]

We have also seen that there are strong similarities between systems containing small amphiphilic molecules on the one hand and diblock copolymers on the other. In both cases, the amphiphiles contain within themselves the properties of the components of two mutually insoluble liquids. The theory of diblock copolymers is more advanced than that of the small molecular systems not only because a simple microscopic model describes most properties of the polymers very well, but also because these properties depend on large-scale behavior of the chains, not small-scale behavior of the monomers. Furthermore, the large polymerization index guarantees that thermal fluctuations are less important than in small molecular systems, so that mean-field theories give very reliable results. [Pg.100]

This book is intended to serve as a reference and/or textbook on the topic of impedance spectroscopy, with special emphasis on its application to solid materials. The goal was to produce a text that would be useful to both the novice and the expert in IS. To this end, the book is organized so that each individual chapter stands on its own. It is intended to be useful to the materials scientist or electrochemist, student or professional, who is planning an IS study of a solid state system and who may have had little previous experience with impedance measurements. Such a reader will find an outline of basic theory, various applications of impedance spectroscopy, and a discussion of experimental methods and data analysis, with examples and appropriate references. It is hoped that the more advanced reader will also find this book valuable as a review and summary of the literature up to the time of writing, with a discussion of current theoretical and experimental issues. A considerable amount of the material in the book is applicable not only to solid ionic systems but also to the electrical response of liquid electrolytes as well as to sohd ones, to electronic as well as to ionic conductors, and even to dielectric response. [Pg.611]

The nematic-smectic A phase transition has attracted a great deal of theoretical and experimental interest because it is the simplest example of a phase transition characterized by translational order. Experiments indicate that it can be first order or more usually continuous, depending on the range of stability of the nematic phase. The critical behaviour that results from a continuous transition is fascinating and allows a test of predictions of the advanced theories for critical phenomena, in an accessible experimental system. In fact, this transition is analogous to the transition from a normal conductor to a superconductor, but is more readily studied in the liquid crystal system. [Pg.255]

Molecularly motivated empiricisms, such as the solubility parameter concept, have been valuable in dealing with mixtures of weakly interacting small molecules where surface forces are small. However, they are completely inadequate for mixtures that involve macromolecules, associating entities like surfactants, and rod-like or plate-like species that can form ordered phases. New theories and models are needed to describe and understand these systems. This is an active research area where advances could lead to better understanding of the dynamics of polymers and colloids in solution, the rheological and mechanical properties of these solutions, and, more generally, the fluid mechaiucs of non-Newtonian liquids. [Pg.86]

Clearly, any measurement that differentiates between the properties of high and low temperature forms of H20(as), and/or delineates the relationship between H20(as) and liquid H20, can be used to test the hypotheses advanced vis a vis their structures. These and the experimental tests suggested, together with the construction of continuous random network models more sophisticated than that for Ge(as), the increased use of computer simulation, and exploitation of the available experimental information to guide the choice of appproximations in a statistical mechanical theory should increase our understanding of H20(as) and, uitimately, liquid H20. [Pg.203]

Robert Hooke, in 1665, was seemingly the next writer to advance the theory of the function of the air in combustion. Hooke concludes that there is a certain substance in the air, which is similar to, if not the same as, a substance contained in saltpeter. This substance has the power to dissolve all combustibles when they are sufficiently heated. Fire may be caused by this solution, which is not merely a phenomenon of motion. The products of this may be aerial, liquid, or solid. In saltpeter this substance is so condensed that there is more of it in a given space than in the same space of air. Combustion in a limited air space ceases when the quantity of this substance in the space is saturated.40 Hooke s promise to explain further this theory was never carried out. Hooke s explanation of combustion is at fault in his supposition of solution instead of combination, and his uncertainty as to what the substance is which in air or in saltpeter supports combustion. [Pg.410]

FLAME EXTINCTION FROM THE UPSTREAM PORTION OF A DROP IN MOTION. In his studies of the influence of relative air velocity on the combustion of liquid fuel spheres, Spalding (51, 56) noted a critical velocity above which flame could not be supported at the upstream portion of the sphere. He observed that the flame blew off and resided solely in the sphere s wake. In tests with kerosine, the air (20° C.) velocity at extinction varied linearly with sphere diameter (range 0.7 to 2.6 cm.), and the ratio Ubi2n was about 100 seconds-1. A similar result is obtained from the data on flame extinction of burning camphor spheres (15, 59). The near proportionality between extinction velocity and diameter was taken as supporting evidence for a theory on flame extinction advanced by Spalding (59). More recent experimental work with porous spheres and n-butyl alcohol as fuel does not support this relationship (1), because it was found that the extinction velocity is proportional to the square root of the drop diameter. [Pg.131]

To conclude, it is probably an understatement to say that, even if the Integral Equation Theories provide, for a given potential, results much faster than simulation methods, the advances in this field progress, however, more slowly than these of its sister method. But, where there is a will, there is a way. Our basic understanding of the liquid state is now at least comparable with our understanding of the physics of solids. [Pg.79]


See other pages where Liquids more advanced theories is mentioned: [Pg.1193]    [Pg.37]    [Pg.299]    [Pg.20]    [Pg.3]    [Pg.224]    [Pg.453]    [Pg.458]    [Pg.171]    [Pg.158]    [Pg.35]    [Pg.46]    [Pg.350]    [Pg.350]    [Pg.327]    [Pg.1]    [Pg.295]    [Pg.800]    [Pg.95]    [Pg.68]    [Pg.126]    [Pg.3]    [Pg.239]    [Pg.102]    [Pg.223]    [Pg.599]    [Pg.263]    [Pg.5]    [Pg.9]    [Pg.128]    [Pg.70]    [Pg.789]    [Pg.451]   
See also in sourсe #XX -- [ Pg.1193 ]




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Liquid theory

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