Intrinsic viscosity values, calculation

Two mobile-phase compositions of H O/CHjCN (80 20, vol/vol) and 0.10 MNaNOj/CHjCN (80 20, vol/vol) were used for SEC-viscometry of partially hydrolyzed grades (32). PEO, PEG, and PSC were used for column calibration, and universal calibration was observed (29). Molecular weights by SEC-viscometry for grades of high, medium, low, and superlow molecular weight compare favorably those from SEC-LALLS, especially with the H O/CHjCN mobile phase (Table 6). It is suspected that the nonsalt mobile phase works better to eliminate the hydrophobic interactions and maximize the size exclusion mechanism (32). Intrinsic viscosity values calculated from viscometry for the two acetonitrile mobile-phase compositions and from Ubbelohde viscometry in HjO/CH CN, are also summarized in Table 6. 

One review [24] considers the theoretical derivation of several such equations, and highlights the effect of polymer concentration and the nature of the solvent in the correlation of intrinsic viscosity values calculated using such equations compared with extrapolated value for [r]]. In summary it should be recognised that ... 

Calculation of the Endocellulase Activity from the Intrinsic Viscosity Values. The enzymic degradation of polymeric substrates can occur at different bonds in the same substrate molecule, and the enzymic activity has to be defined here as the initial number of moles of glyco-sidic bonds split per second (53). This definition corresponds to the definition of the katal, symbolyzed kat. This unit is defined as the catalytic amount of any catalyst (including any enzyme) that catalyzes a reaction rate of one mole per second in an assay system (54), and it is recommended by the International Union of Pure and Applied Chemistry (55) for the quantitative evaluation of catalytic activities. 

The comparison of the received experimentally [r ] and calculated according to the Eq. (10) [rj] intrinsic viscosity values are adduced in Table 24. As one can see, a good correspondence of theory and experiment is obtained (the average discrepancy of [rj] and [rj] makes up approx. 12%). 

Thus, the fractal analysis methods were used above for treatment of comb-like poly(sodiumoxi) methylsylseskvioxanes behavior in solution. It has been shown that the intrinsic viscosity reduction at transition from a linear analog to a branched one is due to the sole factor, namely, to a macromolecule connectivity degree enhancement, characterized by spectral dimension. This conclusion is confirmed by a good correspondence of the experimental and calculated according to Mark-Kuhn-Houwink equation fiactal variant intrinsic viscosity values. It has been shown that qualitative transition of the stmcture of branched polymer macromolecular coil from a good solvent to 0-solvent can be reached by a solvent change. 

The glass transition temperatures of APESF and CP-OF-lO/OS-10 were determined by thermomechanical technique. They are within the range 353-493 K. The T value for F-2 was accepted equal to 503 K [ 11]. The reduced viscosity of copol mers in simm-tetrachloroethane (good solvent) and 1,4-dioxane (0-solvent) was measured with the aid of Ub-belode viscosimeter at temperature 298 K. For the intrinsic viscosity [q] calculation the following relationship was used [12] ... 

The significance of knowing the K and a values of fully hydrolyzed PVA is that molecular weight distribution data can be directly calculated using two methodologies. The first is the Mark-Houwink method, which requires prior knowledge of K and a values for fully hydrolyzed PVA and calibration standards such as PEG, PEO, or PSC. The second method is the intrinsic viscosity method. This method utilizes a simple ratio of the concentration signal to the specific... 

All values were calculated for intrinsic viscosity of gelatin B solutions to 37.4°C and compared against the value of Huggins, normally used as standard. It is noteworthy that each method has a relative error percentage and low for methods of more than four pair s values (Er% > 0.30). 

Once a value for M[ is assumed, this leaves one unknown b which can be determined from the SEC chromatogram and the measured whole polymer intrinsic viscosity in the following manner. First, one estimates a value for b, and calculates M CV) and [n](V) across the chromatogram using the universal calibration curve and equation (3). Then the whole polymer intrinsic viscosity is obtained from... 

The calculated [r[] value is compared with the measured value. Further b values are then tried until the difference between the measured and calculated intrinsic viscosities is minimised. It is also possible to determine both Ml and b if [n] and Mj are known for the whole polymer. 

The effects of calcium on polymer-solvent and polymer-surface interactions are dependent on polymer ionicity a maximum intrinsic viscosity and a minimum adsorption density as a function of polymer ionicity are obtained. For xanthan, on the other hand, no influence of specific polymer-calcium interaction is detected either on solution or on adsorption properties, and the increase in adsorption due to calcium addition is mainly due to reduction in electrostatic repulsion. The maximum adsorption density of xanthan is also found to be independent of the nature of the adsorbent surface, and the value is close to that calculated for a closely-packed monolayer of aligned molecules. 

As shown in Figure 1 data from the viscometer detector and DRI are combined to yield the Intrinsic viscosity as a function of retention volume (la). This curve then was fit to a polynomial and a smoothed curved calculated. At this stage of data reduction the analyst can choose to continue to use the polynomial smoothed values of log [n](V) throughout, or continue to use the unsmoothed values for further data reduction. 

The branching index, g, calculated from the Intrinsic viscosity measurement is related to the g value calculated from the light scattering experiment by the following equations... 

On the other hand, the slope of the lines plotted in Fig, 38, from the value of which the mean life of the chains is calculated, may be greatly effected even by small errors in the determination of the intrinsic viscosity of polymers obtained by shorter time tests. The resulting data are mostly concerned by eventual errors. 

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