Thermodynamic parameters from intrinsic viscosities

Table XLI.—Thermodynamic Parameters Calculated from Intrinsic Viscosities and Their Temperature Coefficients...

Thermodynamic parameters are calculated from intrinsic viscosities and their temperature coelBcients. The values are significantly lower than those obtained by other methods, such as osmotic method (cf. Exercise 3.10) and phase separation studies (see Problem 3.16)... 

TABLE 8.4 Thermodynamic Parameters Obtained from Intrinsic Viscosities... 

Examination of Fig. 17 reveals that the temperature interval over which the transition takes place has a finite breadth, and thus may be characterized by various temperatures defined in different ways. Td, the temperature quoted in Table X, is defined as the temperature of the midpoint of the transition. If one assumes (1) that the fractional change in intrinsic viscosity (or specific rotation) is proportional to the fractional conversion of collagen from a single completely native state to a single completely denatured state, and (2) that equilibrium between these two forms is attained at every temperature, then the relation To = AH/AS applies and these thermodynamic parameters can be calculated from data such as... 

The authors [91] proposed description of organic phase influence on limiting characteristics of polyurethanearylates (PUAr) interfacial polycondensation. As it is known [55], one from the methods of polymer solubility parameter 5 experimental determination is plotting of the dependence of intrinsic viscosity [t ], measured in several solvents, on this solvents solubility parameter 5 value. The smaller difference 6p-5J or the better solvent thermodynamical quality in respect of polymer is, the larger [q] is. The dependences [q](5 ) have usually belllike shape and such dependence maximum corresponds to 5 [55]. In Fig. 23 the dependence of on 5 of solvents, used as organic phase at PUAr interfacial polycondensation is adduced. The dependence q /S ) bell-like shape is obtained again and its maximum corresponds to 5 10 (cal/cm ), that is a reasonable estimation for PUAr [36, 55]. Let us note that all q values were determined in one solvent, which was not used at synthesis, namely, in mixture phenol-simm-tetrachloroethane. The dependence qj 4(5 ), adduced in Fig. 23, allows to make two conclusions. Firstly, the value q, reached in PUAr interfacial polycondensation process, is controlled by solvent thermodynamical qnality and the greatest... 

The chemical composition, dimensions and the molecular parameters of four dental acrylic polymer materials and two polyacrylic acids of different molec.wt. used as model compounds were studied by NMR and IR spectroscopies, GPC, intrinsic viscosity and light scattering measurements. Two of the dental polymers were shown to be mainly polyacrylic acid, while one showed the peak pattern for an acrylic acid/methyl acrylate copolymer of about 2 1 composition and one was an oligomer derived from 2-hydroxyethyl methacrylate. The steric hindrance parameter, molecular stiffness and second virial coefficient were calculated using different thermodynamic models. The Flory-Fox-Shafgagen and the Stockmayer-Fixman models fitted the experimental data reasonably well and could be use to describe the molecular parameters of the acrylic polymers. 18 refs. (7th International Conference on Polymer Characterization (POLYCHAR-7), Denton, Texas, USA, Jan. 1999)... 

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