Intrinsic viscosity-molecular weight relationship

The dilute solution properties of copolymers are similar to those of the homopolymer. The intrinsic viscosity—molecular weight relationship for a VDC—AN copolymer (9 wt % AN) is [77] = 1.06 x 10 (83). The characteristic ratio is 8.8 for this copolymer. 

Intrinsic viscosity—molecular weight relationships have been obtained for copolymers in methyl ethyl ketone. The value for a 15 wt % ethyl acrylate (EA) copolymer is [77] = 2.88 x 10 . ... 

Fig. 50.—Intrinsic viscosity-molecular weight relationship for polyisobutylene in diisobutylene (DIB) at 20° and in cyclohexane at 30°C. Open circles from Ref. 7 filled circles, Ref. 8.

The viscosity average molecular weight depends on the nature of the intrinsic viscosity-molecular weight relationship in each particular case, as represented by the exponent a of the empirical relationship (52), or (55). However, it is not very sensitive to the value of a over the range of concern. For polymers having the most probable distribution to be discussed in the next chapter, it may be shown, for example, that... 

We, therefore, propose an indirect method for obtaining the variation of the intrinsic viscosity and number average molecular weight across the chromatogram. First the intrinsic viscosity-molecular weight relationship for a polymer with long chain branching (LCB) is assumed to be expressable in a form similar to that used by Ram and Milts (6),... 

Fig Intrinsic viscosity-Molecular weight relationships for polyisobutylene in disobutylene and cyclohexane. 

Intrinsic viscosity molecular weight relationship. The values of two constants appearing in the above relation, determined when fractions of a polymer of molecular weights 34000, 61000 and 130000 dissolved in an organic solvent gave the intrinsic viscosities as 1.02,1.60 and 2.75 respectively at 25°C... 

Fig. 24. Intrinsic viscosity-molecular weight relationships for typical polypeptides in helicogenic solvents (O) PELG in TFE (57), ( ) PBLA in m-cresol at 15° C (22% (3) PCBL in DMF at 25° C (23% ( ) PCBL in DMF at 20° C (58)...

Intrinsic Viscosity—Molecular Weight Relationship for PMMA in TFE. The intrinsic viscosities of the PMMA preparative GPC fractions and whole polymers in TFE at 50 °C and in benzene at 30 °C are shown in Table III and plotted in Figure 4. A least-squares analysis of the data plotted in Figure 4 yields the relation... 

K4 Kinsinger, J. B., and R.E. Hughes Intrinsic viscosity-molecular weight relationships for isotactic and atactic polypropylene. J. Phys. Chem. 63, 2002 (1959). 

CR, cryoscopic method DV, diffusion constant and intrinsic viscosity EB, ebullioscopic method EG, end-group titration IV, intrinsic viscosity-molecular weight relationship in other solvents LS, light scattering MV, melt viscosity-molecular weight relationship OS, osmotic pressure PR, analysis of polymerization rate SD, sedimentation and diffusion constants SE, sedimentation equilibrium (Archibald s method) SV, sedimentation constant and intrinsic viscosity [see Eq. (72)]. 

Intrinsic Viscosity - Molecular Weight Relationship. A rod-like polymer has a large a value in the Mark-Houwink equation (Eq. 25). Such an example is poly(y-benzyl L-glutamate)... 

The exponent a in the intrinsic viscosity-molecular weight relationship ([rj] = K.M ) of a polymer is associated with the expansion of the polymer in solution, and hence with the conformation and stiffness of the polymer (Table 24). The a values of tobacco mosaic virus, Kevlar and helical poly(a-amino acids) are close to 2, which means that they take rigid-rod structures. The a values of vinyl polymers are usually 0.5-0.8, indicating randomly coiled structures. In contrast, the a values of substituted polyacetylenes are all about unity. This result indicates that these polymers are taking more expanded conformations than do vinyl polymers. This is atrributed to their polymer-chain stiffness stemming from both the alternating double bonds and the presence of bulky substituents. 

Theoretical treatments on the viscosity of solutions of polymer chains are too numerous to give even a brief summary. Originally their principal objective was to explain the intrinsic viscosity-molecular weight relationship as described in Eq. (5). Now the major interest goes far beyond that and toward a better understanding of the solution properties of polymers. Our brief discussion will be confined only to general terms. The approach... 

Fig. 3. Intrinsic viscosity-molecular weight relationship of poly-7-benzyl-L-glutamates. The open circles represent the randomly coiled form and other symbols the a-helical form. The line of steeper slope is a plot of Simha s equation. Abbreviations dichloroacetic acid, DCA chloroform saturated with formamide, C-F dimethyl formamide, DMF light scattering, L.S. weight-average molecular weight, A/m. Reproduced from Doty et al. (1956).

Figure 7 is a plot of the [lyJ-MW relationship for a multimodal PMMA (Mn 3080, Mw 19,120) superimposed onto the MWD of the sample. The smooth bold curve in this figure represents the literature intrinsic viscosity molecular weight relationship... 

Kar, F. and Arslan, N. 1999b. Effect of temperature and concentration on viscosity of orange peel pectin solutions and intrinsic viscosity-molecular weight relationship, Carbohydr. Polym., 40 277-284. 

The first systematic evaluation of chain dimensions of stereoregular polymers in solution were reported by Danusso and Moraglio2). They studied both isotactic and atactic polystyrene by viscometry and osmometry, in benzene and in toluene, (both thermodynamically good solvents). They concluded that no difference could be observed in the intrinsic viscosity-molecular weight relationship, [tj] = k Ma, for the two stereoregular forms [see Fig. I]. However, they did find a noticeable difference between the second varial coefficients for the two stereoregular forms of equivalent molecular weight. These results were consistent with subsequent measurements on... 

All of these systems showed that, in thermodynamically good solvents, no differences are measurable in the intrinsic viscosity-molecular weight relationship for the different stereoregular forms. In addition, the second varial coefficient, A2, in every case studied was found to be larger for the syndiotactic and atactic forms than for the isotactic forms7, 8> 14,15,19, 25,26). 

Figure 12.17 Intrinsic viscosity-molecular weight relationship. (From Allocock, H.R. and Lampe, F.W., Contemporary Polymer Chemistry, Prendce-Hall, Englewood Cliffs, NJ, 1981. With permission.)...

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