Temperature dependence of the dynamic

To evaluate the full proton hfs tensors for the rigid molecule and to study the temperature dependence of the dynamics of the ring rotation, ENDOR and EI-EPR spectroscopy has been applied to powder samples of these two systems37,78). EPR, ENDOR and EI-EPR data of V(bz)2 diluted into Fe(cp)2 are summarized in Table 18. 

Using the specific entropy determined in the simulations, one can test this theoretical approach by fitting this expression to the temperature dependence of D observed in the simulations. It has been concluded that the Adam-Gibbs theory cannot predict the temperature dependence of the dynamics from the thermodynamic information contained in the temperature dependence of the... 

In principle, the relaxivity of almost all Gd(III) complexes is affected by temperature as a result of the temperature dependence of the dynamic parameters controlling r, namely t/j, tm, and D. Nevertheless, the effect of temperature on the relaxivity is usually rather small and, therefore, of little utility for clinical use. 

Fig. 14. Temperature dependence of the dynamic storage (E ) and loss (E") moduli at 10 Hz as a function of composition...

The temperature dependence of the dynamic fluctuations which contribute to the effective pore size may be estimated by means of mode coupling theory, which views a gel as consisting of N pores of diameter t, over which the density fluctuations are correlated [4, 20, 21]. 

To increase the knowledge of these pure graft copolymers, we determined the temperature dependence of the dynamic mechanical properties of such a product. These measurements were made with the Rheovibron apparatus at a frequency of 110 Hz. 

Fig. 29 Temperature dependence of the dynamic mechanical behaviour, at 11 Hz, for the alternating copolymer B1T1 (from [26])...

To illustrate the transitions occurring in the glassy state, the temperature dependencies of the dynamic mechanical loss tangent at 1 Hz of the DGEBA/HMDA, DGEBA/tetramethylene diamine and DEBA/dodecamethyl-ene diamine systems [65] are shown in Fig. 93. They clearly exhibit two transitions ... 

Fig. 53 Temperature dependence of the dynamic mechanical loss modulus, El, at 1 Hz, for PMMA and various MGIMx copolymers (From [52])...

Motonaga, T., and Shibayama, M. Studies on pH and temperature dependence of the dynamics and heterogeneities in poly(AI-isopropylacrylamide-co-sodium acrylate) gels. Polymer 42 8925-8934, 2001. 

Fig. 4 Temperature dependence of the dynamic storage modulus E and loss modulus E" for CELL/PACMO composites. (Reproduced from [72])...

Although the cured epoxy resins produced by the three typical curing mechanisms have different structure, the temperature dependence of the dynamic mechanical dispersion is similar as shown in Figs. 2 and 3, but Tg is different. Therefore, in order to check the relationship between the structure and Tg, q should be identical. 

The temperature dependence of the dynamic mechanical properties of the cured resins is similar as in Fig. 5 33). This shows that the physical properties of cured resins are mostly characterized by the differences of Tg. 

The temperature dependence of the dynamic modulus of the hydrazide-cured resins is very similar to that of amine-cured resins as shown in Fig. 7. Based on the dynamic mechanical properties of a series of the resins with different and cured by changing... 

The stereoregularity—i.e., distribution of the stereosequence length in these polymers—has a marked effect on the crystallization rates and the morphology of the crystalline aggregates. These differences, in turn, influence the dynamic mechanical properties and the temperature dependence of the dynamic mechanical properties. In order to interpret any differences in the dynamic mechanical properties of polymers and copolymers of propylene oxide made with different catalysts, it was interesting to study the differences in the stereosequence length in the propylene oxide polymers made with a few representative catalysts. 

Figure 3. Effect of acid catalyst (HCl) content on the temperature dependence of the dynamic mechanical parameter tan 8 for a series of TEOS(48)-PDMS(1700)-50-X-80C materials. See text for sample nomenclature. (Reproduced from reference 4. Copyright 1987 American Chemical Society.)...

Figure 8 presents the temperature dependence of the dynamic viscoelasticity of the Si-containing polyacetylenes (23, 24). Poly(2c) shows a dispersion at low temperature because of the presence of the long n-pentyl group. From the sharp increase in tan 8, the glass transition temperature (Tg) of this polymer is about 150 °C. In contrast, poly(3) and poly(4a) hardly show dispersions at low temperature, and their TgS are about 200 or higher. The high Tg values of these polyacetylenes compared with those of most vinyl polymers can be attributed to their stiff main chain. 

Water is well known for its unusual properties, which are the so-called "anomalies" of the pure liquid, as well as for its special behavior as solvent, such as the hydrophobic hydration effects. During the past few years, a wealth of new insights into the origin of these features has been obtained by various experimental approaches and from computer simulation studies. In this review, we discuss points of special interest in the current water research. These points comprise the unusual properties of supercooled water, including the occurrence of liquid-liquid phase transitions, the related structural changes, and the onset of the unusual temperature dependence of the dynamics of the water molecules. The problem of the hydrogen-bond network in the pure liquid, in aqueous mixtures and in solutions, can be approached by percolation theory. The properties of ionic and hydrophobic solvation are discussed in detail. 

Figure 9. Temperature dependence of the dynamic viscosity (cP) of refined sunflower oil [based on (28)].

Now we will discuss a procedure of reconstruction the temperature dependence of the relaxed and unrelaxed elastic moduli. We proposed before that the unrelaxed modulus, which describes the Jahn-Teller contribution, vanishes. Actually, the dynamic modulus measured in an experiment is the total one containing the contribution of the Jahn-Teller system as a summand. So, even the dynamic modulus which contains the unrelaxed Jahn-Teller contribution should be non-zero and can have a certain temperature dependence that is not associated with the Janh-Teller impurities. As well, the relaxed modulus for this reason can differ from one described with the expression (45). To deal with the impurity s contribution only, we can measure the temperature dependence of the dynamic modulus for an un-doped crystal and subtract it from one obtained for the the doped crystal. But it requires two specimens (doped and un-doped) and two experiments. More easy is to reconstruct the relaxed and unrelaxed moduli with the help of the data relating to the doped crystal. To derive the necessary expressions we will use the (20) and (21) and... 

Fig. 4.7 illustrates (4.24). As we can see from the graph, the temperature dependence of the dynamic viscosity and the thermal conductivity can have a marked influence on the heat transfer, as far as they change starkly with the temperature. In condensing steam, for a temperature difference between the saturation and wall temperatures of s — i o < 50 K, the material properties vary for As/Ao between 0.6 and 1.2 and for Vs/vo between 1 and 1.3. This region is hatched in Fig. 4.7. It is clear that within this region the deviations from Nusselt s film condensation theory are less than 3%.

The temperature dependence of the dynamic nuclear polarization enhancement (A ) of the protons in tetrathiafulvalinium tetracyanoquinodi-methane (TTF-TCNQ) and potassium TCNQ (K.TCNQ) is reported. Theoretical expression of A is given experimental results are discussed and allow us to... 

Fig. 13 Temperature-dependence of the dynamic shear modulus G and mechanical loss factor d of different groups of plastics [9]...

Figure 8.24. Temperature dependences of the dynamic storage modulus E and the loss modulus E" of the interpenetrating elastomeric networks. Filled circles observed values. Solid lines calculated for Takayanagi s model 2. Dashed lines component homopolymers. (Klempner et al., 1970.)...

Fig. 229. Temperature dependence of the dynamic Young modulus E for kappa carrageenan gels of various concentrations. The numbers at the curves are the polymer concentrations in wt%. Reproduced from Polym J [Ref. 525] by the courtesy of the authors and The Society of Polymer Science, Japan...

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