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Série The Journal of chemical physics
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The Journal of chemical physics, Vol.19 No12. Statistical Theory of Rubber-Like Elasticity. IV. (Two-Dimensional Stretching) / Akira Isihara
in The Journal of chemical physics
Titre de série : The Journal of chemical physics, Vol.19 No12 Titre : Statistical Theory of Rubber-Like Elasticity. IV. (Two-Dimensional Stretching) Type de document : articles et extraits Auteurs : Akira Isihara, Auteur ; N. Hashitsume, Auteur ; Masao Tatibana, Auteur Année de publication : 1951 Importance : p.1508-1512 Langues : Français (fre) Résumé : The failure, revealed by the experiment of Treloar, of statistical theories of the rubber-like elasticity is removed. It comes from the neglection of the nongaussian character and of the nonlinear connectivity of the network structure. The theoretical formula derived here includes the semi-empirical formula given by Treloar
in The Journal of chemical physics
The Journal of chemical physics, Vol.19 No12. Statistical Theory of Rubber-Like Elasticity. IV. (Two-Dimensional Stretching) [articles et extraits] / Akira Isihara, Auteur ; N. Hashitsume, Auteur ; Masao Tatibana, Auteur . - 1951 . - p.1508-1512.
Langues : Français (fre)
Résumé : The failure, revealed by the experiment of Treloar, of statistical theories of the rubber-like elasticity is removed. It comes from the neglection of the nongaussian character and of the nonlinear connectivity of the network structure. The theoretical formula derived here includes the semi-empirical formula given by Treloar Réservation
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Code-barres Cote Support Localisation Section Disponibilité ART-19511508 ISI Document imprimé Bureau chercheur Bureau de Christophe Clanet Disponible The Journal of chemical physics, Vol.19 No12. Statistical Thermodynamics of Rubber Elasticity / Frederick T. Wall
in The Journal of chemical physics
Titre de série : The Journal of chemical physics, Vol.19 No12 Titre : Statistical Thermodynamics of Rubber Elasticity Type de document : articles et extraits Auteurs : Frederick T. Wall, Auteur ; Paul J. Flory, Auteur Année de publication : 1951 Importance : P. 1435-1439 Langues : Français (fre) Résumé : Two principal differences between the theories of rubber elasticity advanced by James and Guth and by other authors are examined in the light of certain fundamental concepts. First the distribution functions for molecular chain lengths in vulcanized rubber networks are considered from the point of view of symmetry. Assuming a relaxed network to be isotropic and a network subject to uniform stress in one direction to be transversely isotropic, it is possible to formulate very general mathematical forms with respect to which the actual distribution functions must be compatible. It is shown that the functions employed by Wall and by Flory and Rehner are consistent with the required general forms; those of James and Guth are incompatible with any degree of isotropy and suggest an aeolotropic structure for vulcanized rubber.It is also shown that the configurational entropy of vulcanization must be zero and quite independent of the statistical nature of the chains comprising the network, providing the network is not deformed macroscopically. The negative entropy of vulcanization derived by James and Guth arises from their erroneous identification of the configurational probability with the number of configurations which a microscopically specified network structure could assume, rather than with the total number of configurations for all network structures which are consistent with the requirements of the vulcanization process. The assertion of James and Guth that the configurations of the polymer chains are altered in some systematic manner by the introduction of cross-linkages and their concept of ``internal pressure'' originate in this error. The present article attempts to clarify the currently prevalent confusion with respect to rubber elasticity theory. The Journal of Chemical Physics is copyrighted by The American Institute of Physics.
in The Journal of chemical physics
The Journal of chemical physics, Vol.19 No12. Statistical Thermodynamics of Rubber Elasticity [articles et extraits] / Frederick T. Wall, Auteur ; Paul J. Flory, Auteur . - 1951 . - P. 1435-1439.
Langues : Français (fre)
Résumé : Two principal differences between the theories of rubber elasticity advanced by James and Guth and by other authors are examined in the light of certain fundamental concepts. First the distribution functions for molecular chain lengths in vulcanized rubber networks are considered from the point of view of symmetry. Assuming a relaxed network to be isotropic and a network subject to uniform stress in one direction to be transversely isotropic, it is possible to formulate very general mathematical forms with respect to which the actual distribution functions must be compatible. It is shown that the functions employed by Wall and by Flory and Rehner are consistent with the required general forms; those of James and Guth are incompatible with any degree of isotropy and suggest an aeolotropic structure for vulcanized rubber.It is also shown that the configurational entropy of vulcanization must be zero and quite independent of the statistical nature of the chains comprising the network, providing the network is not deformed macroscopically. The negative entropy of vulcanization derived by James and Guth arises from their erroneous identification of the configurational probability with the number of configurations which a microscopically specified network structure could assume, rather than with the total number of configurations for all network structures which are consistent with the requirements of the vulcanization process. The assertion of James and Guth that the configurations of the polymer chains are altered in some systematic manner by the introduction of cross-linkages and their concept of ``internal pressure'' originate in this error. The present article attempts to clarify the currently prevalent confusion with respect to rubber elasticity theory. The Journal of Chemical Physics is copyrighted by The American Institute of Physics. Réservation
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Code-barres Cote Support Localisation Section Disponibilité ART-19511435 WAL Document imprimé Bureau chercheur Bureau de Christophe Clanet Disponible The Journal of chemical physics, Vol.21 No.6. Statistical Thermodynamics of Rubber Elasticity / Hubert M. James
in The Journal of chemical physics
Titre de série : The Journal of chemical physics, Vol.21 No.6 Titre : Statistical Thermodynamics of Rubber Elasticity Type de document : articles et extraits Auteurs : Hubert M. James, Auteur ; Eugene Guth, Auteur Année de publication : 1953 Importance : p. 1039-1049 Langues : Français (fre) Résumé : The basic concepts and procedures underlying the theory of rubber elasticity are analyzed. The arguments advanced by Wall and Flory against the network theory of the authors are shown to be without foundation. The alternative theory which they advocate, and which is rather widely used, is criticized on two grounds: (a) it assumes a distribution of chain extensions that does not vary with network extension in the way the actual distribution functions can be shown to vary, and (b) the methods used to compute the numbers of network configurations from the distributions of chain extensions are invalid, except in the most trivial cases. The concept of ``interval dilation entropy'' is discussed and is shown to lack any physical basis. It is concluded that all the methods of calculation that lead to logarithmic terms in the network configuration entropy are incorrect, and that these terms, which affect the theory of swelling, should be discarded.
in The Journal of chemical physics
The Journal of chemical physics, Vol.21 No.6. Statistical Thermodynamics of Rubber Elasticity [articles et extraits] / Hubert M. James, Auteur ; Eugene Guth, Auteur . - 1953 . - p. 1039-1049.
Langues : Français (fre)
Résumé : The basic concepts and procedures underlying the theory of rubber elasticity are analyzed. The arguments advanced by Wall and Flory against the network theory of the authors are shown to be without foundation. The alternative theory which they advocate, and which is rather widely used, is criticized on two grounds: (a) it assumes a distribution of chain extensions that does not vary with network extension in the way the actual distribution functions can be shown to vary, and (b) the methods used to compute the numbers of network configurations from the distributions of chain extensions are invalid, except in the most trivial cases. The concept of ``interval dilation entropy'' is discussed and is shown to lack any physical basis. It is concluded that all the methods of calculation that lead to logarithmic terms in the network configuration entropy are incorrect, and that these terms, which affect the theory of swelling, should be discarded. Réservation
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Code-barres Cote Support Localisation Section Disponibilité ART-19531039 JAM Document imprimé Bureau chercheur Bureau de Christophe Clanet Disponible The Journal of chemical physics, Vol.77 No.12. Adsorption of polymer chains at surfaces: Scaling and Monte Carlo analyses / E. Eisenriegler
in The Journal of chemical physics
Titre de série : The Journal of chemical physics, Vol.77 No.12 Titre : Adsorption of polymer chains at surfaces: Scaling and Monte Carlo analyses Type de document : articles et extraits Auteurs : E. Eisenriegler, Auteur ; K. Binder, Auteur ; K. Kremer, Auteur Année de publication : 1982 Importance : p.6296-6320 Langues : Français (fre) Résumé : The influence of a hard wall on the configurations of long flexible polymer chains near the wall is studied, in the presence of a short-range attractive force between monomers and the wall. Particular attention is paid to the region around the temperature Ta below which the polymer becomes adsorbed to the wall, i.e., where the typical polymer linear dimensions perpendicular to the wall become independent of chain length. Both ideal noninteracting chains and chains with excluded volume interactions are treated. Polymer linear dimensions parallel and perpendicular to the wall and their probability distributions are studied, as well as the behavior of the monomer fraction at the surface and a distance z in the interior. The relation of polymer statistics to the problem of correlation functions in the n-vector model of magnetism in the limit n0 is exploited to express both the exponents describing the various power laws and the crossover scaling functions near Ta in terms of results for the analogous problem of the critical behavior of magnets with a free surface. The predictions of this scaling theory are confirmed by Monte Carlo studies of self-avoiding walks on the tetrahedral lattice with a free surface, and estimates for the exponents involved are presented. A new sampling technique with a bias in favor of adsorbed polymer configurations is developed.
in The Journal of chemical physics
The Journal of chemical physics, Vol.77 No.12. Adsorption of polymer chains at surfaces: Scaling and Monte Carlo analyses [articles et extraits] / E. Eisenriegler, Auteur ; K. Binder, Auteur ; K. Kremer, Auteur . - 1982 . - p.6296-6320.
Langues : Français (fre)
Résumé : The influence of a hard wall on the configurations of long flexible polymer chains near the wall is studied, in the presence of a short-range attractive force between monomers and the wall. Particular attention is paid to the region around the temperature Ta below which the polymer becomes adsorbed to the wall, i.e., where the typical polymer linear dimensions perpendicular to the wall become independent of chain length. Both ideal noninteracting chains and chains with excluded volume interactions are treated. Polymer linear dimensions parallel and perpendicular to the wall and their probability distributions are studied, as well as the behavior of the monomer fraction at the surface and a distance z in the interior. The relation of polymer statistics to the problem of correlation functions in the n-vector model of magnetism in the limit n0 is exploited to express both the exponents describing the various power laws and the crossover scaling functions near Ta in terms of results for the analogous problem of the critical behavior of magnets with a free surface. The predictions of this scaling theory are confirmed by Monte Carlo studies of self-avoiding walks on the tetrahedral lattice with a free surface, and estimates for the exponents involved are presented. A new sampling technique with a bias in favor of adsorbed polymer configurations is developed.
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Code-barres Cote Support Localisation Section Disponibilité ART-7181-0 ART Document imprimé Bureau chercheur Bureau de FRISCH Thomas Disponible The Journal of chemical physics, Vol.13 No.2. Further studies of the structure and stability of burner flames / G. Von Elbe
in The Journal of chemical physics
Titre de série : The Journal of chemical physics, Vol.13 No.2 Titre : Further studies of the structure and stability of burner flames Type de document : articles et extraits Auteurs : G. Von Elbe, Auteur ; M. Mentser, Auteur Année de publication : 1945 Importance : p.89-100 Langues : Français (fre) Résumé : It is shown that, contrary to Mache's model of the progressive extinction of a flame from the burner rim, a combustion zone cannot vanish within a combustible stream. The depth of penetration of the quenching of the explosive reaction by the burner wall is calculated from values of burning velocity and critical boundary velocity gradient for flashback; it is compared with the limiting distance between plane-parallel plates and the limiting tube diameter for flame propagation. The thermal expansion of the gas normal and parallel to the combustion zone is discussed. An experimental analysis and discussion of partial entrance of the combustion zone into the burner tube (tilted flame) and partial attachment to the burner rim are given. New data have been obtained on hydrogen and acetylene flames. For instantaneous flashback, the boundary velocity gradients are independent of tube diameter, as expected; these gradients are not a satisfactory criterion for flame stability because flashback can be readily induced by tilted flames. The limit of the tilted-flame range is represented by the semitheoretical equation [dformula g/(1--4S[sub u]/gR)[sup (1/2)] [equals sign] const.] g is the boundary-velocity gradient, Su the burning velocity, and R the tube diameter. The boundary-velocity gradients for blow-off are again found constant over the laminar flow range. The compression of acetylene-oxygen streams by the combustion zone has been measured. The burning velocities calculated from these and additional thermodynamic data agree well with those determined from gas flow and cone surface. The Journal of Chemical Physics is copyrighted by The American Institute of Physics.
in The Journal of chemical physics
The Journal of chemical physics, Vol.13 No.2. Further studies of the structure and stability of burner flames [articles et extraits] / G. Von Elbe, Auteur ; M. Mentser, Auteur . - 1945 . - p.89-100.
Langues : Français (fre)
Résumé : It is shown that, contrary to Mache's model of the progressive extinction of a flame from the burner rim, a combustion zone cannot vanish within a combustible stream. The depth of penetration of the quenching of the explosive reaction by the burner wall is calculated from values of burning velocity and critical boundary velocity gradient for flashback; it is compared with the limiting distance between plane-parallel plates and the limiting tube diameter for flame propagation. The thermal expansion of the gas normal and parallel to the combustion zone is discussed. An experimental analysis and discussion of partial entrance of the combustion zone into the burner tube (tilted flame) and partial attachment to the burner rim are given. New data have been obtained on hydrogen and acetylene flames. For instantaneous flashback, the boundary velocity gradients are independent of tube diameter, as expected; these gradients are not a satisfactory criterion for flame stability because flashback can be readily induced by tilted flames. The limit of the tilted-flame range is represented by the semitheoretical equation [dformula g/(1--4S[sub u]/gR)[sup (1/2)] [equals sign] const.] g is the boundary-velocity gradient, Su the burning velocity, and R the tube diameter. The boundary-velocity gradients for blow-off are again found constant over the laminar flow range. The compression of acetylene-oxygen streams by the combustion zone has been measured. The burning velocities calculated from these and additional thermodynamic data agree well with those determined from gas flow and cone surface. The Journal of Chemical Physics is copyrighted by The American Institute of Physics.
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Code-barres Cote Support Localisation Section Disponibilité ART-8574-0 ART Document imprimé Bureau chercheur Bureau de TRUFFAUT Jean Marie Disponible The Journal of chemical physics, Vol.18. On the stability of gas bubbles in liquid-gas solutions / P. S. Epstein
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Titre de série : The Journal of chemical physics, Vol.18 Titre : On the stability of gas bubbles in liquid-gas solutions Type de document : articles et extraits Auteurs : P. S. Epstein, Auteur ; M. S. Plesset, Auteur Année de publication : 1950 Importance : p.1505-1509 Langues : Français (fre)
in The Journal of chemical physics
The Journal of chemical physics, Vol.18. On the stability of gas bubbles in liquid-gas solutions [articles et extraits] / P. S. Epstein, Auteur ; M. S. Plesset, Auteur . - 1950 . - p.1505-1509.
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Code-barres Cote Support Localisation Section Disponibilité ART-8935-0 ART Document imprimé Bureau chercheur Bureau de CAILLE François Disponible The Journal of chemical physics, Vol.23 No.6. Calculation of Thermodynamic Properties of Polyelectrolytes / R. A. Marcus
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Titre de série : The Journal of chemical physics, Vol.23 No.6 Titre : Calculation of Thermodynamic Properties of Polyelectrolytes Type de document : articles et extraits Auteurs : R. A. Marcus, Auteur Année de publication : 1955 Importance : p.1057-1068 Langues : Français (fre)
in The Journal of chemical physics
The Journal of chemical physics, Vol.23 No.6. Calculation of Thermodynamic Properties of Polyelectrolytes [articles et extraits] / R. A. Marcus, Auteur . - 1955 . - p.1057-1068.
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Code-barres Cote Support Localisation Section Disponibilité ART-9350-0 ART Document imprimé Bureau chercheur Bureau de LEONETTI Marc Disponible The Journal of chemical physics, Vol.84 No.8. Spreading of liquid drops on thin cylinders: The ``manchon/droplet''transition / F. Brochard
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Titre de série : The Journal of chemical physics, Vol.84 No.8 Titre : Spreading of liquid drops on thin cylinders: The ``manchon/droplet''transition Type de document : articles et extraits Auteurs : F. Brochard, Auteur Année de publication : 1986 Importance : p.4664-4672 Langues : Français (fre) Résumé : We discuss the spreading of liquids on thin cylinders (radius b), including the effects of long range attractive van der Waals (VW) forces. For volatile liquids, the vapor adsorbs on the cylinders; the thickness e of the film is given by a balance between the disjoining VW pressure and Laplace pressure (e3=ba2, where a is a molecular size). For nonvolatile liquids, a liquid drop cannot spread out over the cylinder if the spreading coefficient S is smaller than a critical value Sc. For S=Sc, we find a first order transition between a droplet and a sheath structure (``manchon''). For S>Sc the droplet spreads indefinitely. The thickness of the manchon is equal to the thickness reached by a drop spreading over a plane surface. We also calculate the liquid profile just below the threshold Sc. When S-->Sc, a precursor manchon appears at the two poles of the droplets.
in The Journal of chemical physics
The Journal of chemical physics, Vol.84 No.8. Spreading of liquid drops on thin cylinders: The ``manchon/droplet''transition [articles et extraits] / F. Brochard, Auteur . - 1986 . - p.4664-4672.
Langues : Français (fre)
Résumé : We discuss the spreading of liquids on thin cylinders (radius b), including the effects of long range attractive van der Waals (VW) forces. For volatile liquids, the vapor adsorbs on the cylinders; the thickness e of the film is given by a balance between the disjoining VW pressure and Laplace pressure (e3=ba2, where a is a molecular size). For nonvolatile liquids, a liquid drop cannot spread out over the cylinder if the spreading coefficient S is smaller than a critical value Sc. For S=Sc, we find a first order transition between a droplet and a sheath structure (``manchon''). For S>Sc the droplet spreads indefinitely. The thickness of the manchon is equal to the thickness reached by a drop spreading over a plane surface. We also calculate the liquid profile just below the threshold Sc. When S-->Sc, a precursor manchon appears at the two poles of the droplets.
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Code-barres Cote Support Localisation Section Disponibilité ART-9523-0 ART Document imprimé Bureau chercheur Bureau de VILLERMAUX Emmanuel Disponible