Jones and Stockmayer model

The value of calculated from Wg and corresponding to the polystyrene Interpretation is 0.72 ns which is in good agreement with the time scale of the Jones and Stockmayer model. 

Since none of the lattice models is now clearly superior, the choice for interpretation of spin relaxation in polymers is arbitrary. Familiarity leads us to select the Jones and Stockmayer model so we will now consider application of this model to several well studied polymer systems in order to compare dynamics from polymer to polymer. Also the equations required to consider anisotropic Internal rotation of substituent groups and overall molecular tumbling as independent motions in addition to backbone rearrangements caused by the three-bond jump are available for the Jones and Stockmayer model (13). 

Another solution is to use the master equation in its discrete from and to perform an exact mode analysis on the resulting Hiickel matrix arbitrarily truncated. In such a case the truncation is directly associated with the finite length of the chain which is taken into account in the calculation. In fact, this procedure, proposed by Jones and Stockmayer does not lead to a closed expression for the OACF, but to an infinite series of expressions corresponding to different truncations. This makes the comparison of the J S mddel with experiments rather lengthy. Since similar ideas can now be accounted for by closed expressions, we will not present here the detailed discussion of the JS model (for a more complete discussion, see Ref. 

In addition to determining the time scales for several local motions in polyformal, two different interpretational models for segmental motion will be employed. An older model by Jones and Stockmayer (7 ), based on the action of a three bond jump on a tetrahedral lattice is compared with a new model by Weber and Hel-fand (8), based on computer simulations of polyethylene type chains. These two models for segmental motion have been compared before (5 ) for two polycarbonates but somewhat different results are seen in the polyformal interpretation. 

We shall be concerned with fluids in the liquid rather than gaseous state and with their classical rather than quantum-mechanical description. Our detailed illustrative examples will be further restricted to a few sample model potentials, although our ultimate goal includes the treatment of polyatomic molecules, real electrolytes, and fused salts as well as the sorts of models—the Lennard-Jones and Stockmayer fluids and the primitive-model ionic solution—that have already been treated accurately by the techniques herein. Recent theoretical developments that promise to transform our goal from a vision into a well-defined research program lie beyond the rather narrow sights... 

Properties.—Carbon-13 and field-dependent proton spin-lattice relaxation times have been measured as a function of temperature and molecular weight for solutions of polycarbonates in CDCI3. The spin-lattice relaxation times were interpreted in terms of segmental motion, characterized by the sharp cut-off model of Jones and Stockmayer, for phenyl group rotation and methyl group rotation. ... 

Binary Mixtures—Low Pressure—Polar Components The Brokaw correlation was based on the Chapman-Enskog equation, but 0 g and were evaluated with a modified Stockmayer potential for polar molecules. Hence, slightly different symbols are used. That potential model reduces to the Lennard-Jones 6-12 potential for interactions between nonpolar molecules. As a result, the method should yield accurate predictions for polar as well as nonpolar gas mixtures. Brokaw presented data for 9 relatively polar pairs along with the prediction. The agreement was good an average absolute error of 6.4 percent, considering the complexity of some of... 

The applicability of the Jones-Stockmayer (JS)74 model to the relaxation of polysaccharides was tested first by Matsuo9 for linear dextrans and amylose in... 

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