Thermodynamics, rubbers solution

G. Gee, Thermodynamics of rubber solutions and gels, in Advances in Colloid Science, Vol. 2, Interscience, New York (1946). 

VSH Vshivkov, S.A. and Rusinova, E.V., Thermodynamics of solutions of blends of diene rubbers under deformation (Russ.), Vysokomol. Soedin., Ser. B, 46, 912, 2004. 

The evidence comes from a variety of sources from Investigations on rubber elasticity, chemical cycllzatlon equilibria, thermodynamics of solutions, and, most recently, from neutron scattering studies on protonated polymers In deuterated hosts (or vice versa).The Investigations last mentioned go further. They confirm the prediction made twenty-five years ago that the excluded volume perturbation should be annulled in the bulk amorphous state. The excluded volume effect is therefore an aberration of the dilute solution, which, unfortunately. Is the medium preferred for physicochemical characterization of macromolecules. 

In Geneva, he resumed with new energy his studies of macromolecules. He was able to obtain the cooperation of A. J. H. van der Wijk, who was one of his most devoted coworkers the latter s realistic criticisms were a valuable balance to Meyer s great enthusiasm. Studies on the thermodynamics of large molecules in solution, and on the structure of cellulose and chitin, were pursued with C. Boissonnas, W. Lothmar, and L. Misch. A theory of the elasticity of rubber evolved from his work with C. Ferri and his previous observations with Susich and Valk6. 

Finally, we turn from solutions to the bulk state of amorphous polymers, specifically the thermoelastic properties of the rubbery state. The contrasting behavior of rubber, as compared with other solids, such as the temperature decrease upon adiabatic extension, the contraction upon heating under load, and the positive temperature coefficient of stress under constant elongation, had been observed in the nineteenth century by Gough and Joule. The latter was able to interpret these experiments in terms of the second law of thermodynamics, which revealed the connection between the different phenomena observed. One could conclude the primary effect to be a reduction of entropy... 

Swollen tensile and compression techniques avoid both of these problems since equilibrium swelling is not required, and the method is based on interfacial bond release and plasticization rather than solution thermodynamics. The technique relies upon the approach to ideal rubberlike behavior which results when lightly crosslinked polymers are swelled. At small to moderate elongations, the stress-strain properties of rubbers... 

Both modifications affect the analysis of dilute solution behavior, and it is difficult to judge how much the e/e0 term is actually needed. In any case, as the authors themselves point out (41), the e/e0 term makes an entirely negligible contribution to solvent activity in concentrated solutions. For example, simple calculations yield a contribution of approximately l%ina 10% solution of natural rubber in benzene at 30° C (M = 500000, [t/]g = 250, y=0.4). It is therefore clear that thermodynamic measurements can furnish no evidence for or against continued collapse in concentrated solutions. 

Maron, S. H., Nakajima, N. A theory of the thermodynamic behavior of non electrolyte solutions. II. Application to the system benzene-rubber. J. Polymer Sci. 40, 59-71... 

S 4. Scott, R. L and M. Magat Thermodynamics of high-polymer solutions. III. Swelling of cross-linked rubber. J. Polymer Sci. 4, 555 (1949). 

Since the pioneering work of Kuhn, the solvent freezing point depression observed in swollen crosslinked rubbers has been the subject of many works. The observed AT can be attributed to two origins. A sizable AT is accounted for by the lowering of the thermodynamic potential of solvent molecules in a polymer solution derived from the Flory theory, and the additional AT observed for crosslinked rubbers has been attributed to confinement effects, fn 1991, Jackson and McKenna [32] studied... 

In 4.3 we have already seen that polymers, in the rubber or fluid condition, crystallize much more rapidly when their chains are oriented. Therefore a stretched rubber, if stereospecific in its molecular structure, is able to crystallize at a temperature considerably above its equilibrium thermodynamic melting point. Also a thermoplast such as polyethylene, when in the molten state or in solution, can crystallize spontaneously when the chains are being orientated in elongational flow. The latter case is utilized when polyethylene is spun from a diluted solution (gel spinning process), resulting in fibres of super-high strength and stiffness ( Dyneema fibres). 

Chemical Thermodynamics Coordination Compounds Electrolyte Solutions, Transport Properties Fluid Mixing Mineral Processing Petroleum Refining Pharmaceuticals Rubber, Synthetic Synthetic Fuels... 

Eichinger, B. E. Flory, P. J., "Thermodynamics of Polymer Solutions. Part 1. Natural Rubber and Benzene," Trans. Faraday Soc., 64, 2035 (1968d). 

While studying polymer distribution between the emulsion phases it was found that in the systems mentioned above obtained both by copolymerization of styrene with polybutadiene rubber and mixing styrene solutions of polymers when the composition is far enough from the critical mixing point, thermodynamic equilibrium is reached.At this thermodynamic equilibrium the ratio of polymer concentration (Cp) in rubber (index ) as well as in polystyrene (index ) phases is practically constant (table II),... 

With the basic structure of polymers of macromolecules clarified, scientists now searched for a quantitative understanding of the various polymerization processes, the action of specific catalysts, and initiation and inhibitors. In addition, they strived to develop methods to study the microstructure of long-chain compounds and to establish preliminary relations between these structures and the resulting properties. In this period also falls the origin of the kinetic theory of rubber elasticity and the origin of the thermodynamics and hydrodynamics of polymer solutions. Industrially polystyrene, poly(vinyl chloride), synthetic rubber, and nylon appeared on the scene as products of immense value and utility. One particularly gratifying, unexpected event was the polymerization of ethylene at very high pressures. 

The above thermodynamic expressions for a binary solution of a polymer in a solvent include the dimensionless parameter Its value can be determined by measuring any of the experimentally obtainable quantities, like solvent activity or the osmotic pressure of the solution. The constancy of %, over a wide composition range would be a confirmation of the validity of the Flory-Huggins theory. Figure 12.10 represents such a plot obtained by the measurement of solvent activities for various systems. Only in the case of the nonpolar rubber-benzene system was the predicted constancy of %, observed other systems showed marked deviations from theory. 

D. Patterson, Thermodynamics of non-dilute polymer solutions. Rubber Chem. Technol. 40, 1 (1967). 

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