Intrinsic viscosity Huggins constant

Table 1. Intrinsic Viscosities, Huggins Constants, and Viscosity-Average Molecular Weights for the Polymers Examined in this Investigation...

The main aim of this study was to investigate the effects of the origin and amount of proteins on the aggregation of xanthan chains in solution by means of rheological measurements. Modifications of fermentation conditions led to variations of intrinsic viscosity, Huggins constant and pyruvate content of the xanthan produced. 

Table 18.3 Intrinsic Viscosities, Huggins Constants (Kh), and Kraemers Constants (Kk) of PANI in NMP and DMPU...

The intrinsic viscosity [ti] and Huggins constant Kjj were calculated according to Huggins equation (11). 

Sam- ple Nr Method for obtaining Polysaccharide yield g/L culture medium, g Polyuronides DE, PUAC, % % Molecular mass Intrinsic viscosity dlxg" Huggins constant Kh... 

Sam- ple Nr Kind of initial material for pectin extraction Extraction time min Yield of pectin, g per 200 g fresh material AUAC, % DE, % Molecul mass Mv Huggins constant Kh Intrinsic viscosity [ft] dl.g- Gel. strengtl TB... 

We have recently performed systematical measurements of the intrinsic viscosity of acrylamide-acrylic acid copolymers for large ranges of r and a, in the presence of CaCl2(26). Our results show that the empirical relation (14) can be extended to the case of divalent cations by using the value of 7 given in relation (15). It should then possible to predict the variation of intrinsic viscosity at infinite dilution, but at finite concentration the formation of aggregates makes difficult the determination of the Huggins constant. 

Figure2. Effect of calcium on intrinsic viscosity and Huggins constant of HPAM.

In many ways it would have been desirable to have obtained a continuous record during the reaction of the intrinsic viscosity, [rf], which can be found by extrapolating to zero concentration of the function rj/c. However, no convenient experimental procedure was devised for doing this, and no extrapolation formula could be used since the Huggins constant for the polymer changed during the reaction. 

Figure 14. Huggins constant, k1 and intrinsic viscosity in toluene at 25°C. for styrene-hydroxyethyl methacrylate copolymer (2.2 mole % HEM A) after crosslinking with hexamethylene diisocyanate in toluene at 80°C.

Solution Viscosity. The intrinsic viscosities [77] of the copolymers were measured for solutions in dry toluene at 25 °C. by dilution in an Ubbelohde suspended-level viscometer. Conventional plots of rj/c (18) and log (1 + r )/c (29) were found to be nonlinear for all copolymers where 77 is the specific viscosity. To get accurate values of the intrinsic viscosities and of the Huggins constants h and k2, triple plots were drawn as recommended by Heller (16). These gave the intercept 1/[iy], and fci and were determined directly from the initial slopes of the plots... 

The intrinsic viscosity as well as the Huggins constants were measured for polyMAOT and polyAOT (Table 12). The intrinsic viscosity for polyMAOT is larger than that for polyAOT, probably because of the difference in molecular weight27. The value varies significantly with change of solvent, and the Huggins constant also vary with the solvent used in a similar manner. 

Over the years, several authors tried to correlate polymer-polymer miscibility with solution viscosity in a common solvent [Bohdanecky and Kovar, 1982]. An interesting report in this field was published by Chee [1990]. The author considered that the parameter b = kjj[ri] (kjj is the Huggins constant of Eq 2.37, and [r ] is the intrinsic viscosity) is a measure of the interactions between solvent and the polymeric species. For polymer blends, the author wrote ... 

It was assumed that the solutions were Newtonian at the shear rates in the capillary. This assumption was assessed with Couette viscometer measurements of these dilute solutions over a range of shear rates and was reasonable. Deviations were found for solutions at the higher concentrations, as indicated by negative departure from linearity of the reduced-viscosity-concentration plots these values were not used for intrinsic viscosity and Huggins constant determination. 

Hydrophobic associations can dominate polymer conformation in solution and solution rheological properties. Intrinsic viscosity and Huggins interaction coefficients provided information on the conformation and intramolecular aggregation behavior of these polymers in dilute solution. The presence of hydrophobic associations caused a decrease in the intrinsic viscosity and an increase in the Huggins constant. These effects could be counterbalanced by increasing the ionic charge on the polymer through hydrolysis or by copolymerization with sodium acrylate. 

For calculation of the intrinsic viscosity [rj] of PSD solutions in tetra-hydrofuran Mark-Kuhn-Houwink equation fractal variant (the Eq. (10)) was used, where the constant c(a) is accepted equal to 2.91. and values, received experimentally, are adduced in Table 24 and value for PSD was calculated as follows. As it is known through Ref [1], for flexible-chain polymers, having a l, Huggins constant can be determined according to the Eq. (174), from which it follows that the condition cc l is fulfilled for the values k 0.55. The Table 24 data showed that the last... 

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