In this case, G is estimated as 2990 kg/mzs using the Omega method (calculation not shown). [Pg.74]

The viscosity average,Mv, does not belong to the series Mn, MW,MZ etc. The measurement does not supply an absolute value of the molar mass, but can, by contrast with the other methods mentioned so far, be carried out in an easy way. Its principle is, that a polymer, even at very low concentrations, brings about a significant viscosity increase of the solvent. This increase is not only dependent on the concentration but also on the molar mass. The measurement is carried out as follows (see also Qu. 2.14 - 2.18 and 2.31 - 2.34) [Pg.35]

For synthesized carbosiloxane polymers, MMD curves were determined by the gel permeation chro-matography (GPC) method. Table 14 shows Mco, Mco/Mn and Mz/Mco values for polymers with dif-ferent sizes of cyclic fragment, from cyclotetrasiloxane to cyclooctasiloxane. [Pg.198]

There are several ways of determining T, the most reliable method probably being saturation-recovery, in which two 90° pulses are applied separated by a time x of the order of Ti. The signal height is then proportional to Mz(x), given by [Pg.183]

Molecular mechanics is essentially empirical, while methods like PPP, CNDO, and AM1/PM3 are semiempirical. What are the analogies in PPP etc. to MM procedures of developing and parameterizing a forcefield Why are PPP etc. only. sY mz empirical [Pg.444]

Thus a plot of 1/Mw ipp(cell) vs. c0, could yield B from the limiting slope, and BLs could be estimated from Equation 90, provided one had an estimate of Mz, the z-average molecular weight. This method was restricted to lower speeds (to avoid solute redistribution problems) and to solutions that were not too nonideal. More recently, Deonier and Williams (37) showed that [Pg.261]

Few sedimentation or diffusion measurements have been made on the starch components, although methods of estimating polymolecularity of samples from sedimentation136 and diffusion136 measurements have been evaluated. The molecular-weight distribution can also be obtained from comparisons of Mn, Mw, and Mz, 137 and more directly by fractional pre- [Pg.358]

Truncated Newton methods can be competitive only with preconditioning. Thus, the operation count for obtaining p in TN reflects IT inner PCG iterations per Newton step. Each such inner iteration involves the following operations an Hd multiplication (an, for an additional gradient evaluation in this finite-difference approximation [58]) calculation of the PCG vectors and scalars (7 , Algorithm [A4]) and numerical solution of Mz = r by forward and backward substitution (0(1), see [61]). [Pg.50]

SEC or gel permeation chromatography (GPC) is one of the widely used chromatographic techniques [56,57]. In contrast to the already discussed colligative and scattering methods it is not an absolute method and requires proper calibration with some known polymer standards. One obtains not only the average molar masses (M , Mw, Mz) but the complete molar mass distributions. [Pg.228]

Three issues have to be resolved in order to measure this equilibrium electrode potential (1) the selection of a reference electrode (2) the coupling of the reference electrode with the electrode whose potential is being measured, in this case M/Mz+ and (3) the experimental method for the voltage measurement. [Pg.58]

It is shown that the temperature coefficient of this dehydrocondensation reaction equals y=1.5. From the dependence of the reaction rate constants logarithm on reverse temperature, the activation energy of the reaction was calculated, which equals Ea = 32.55 kJ/mol. For copolymers N°7 and 9 (Table 16), quantitative values of Mn, Mco, Mz and Mco/ Mn were determined by gel permeation chromatography methods, which equal Mn=1.05-1.62xl04 and Mco-1.69-1.98/ 104 polydispersion degrees, D, of copolymer N 7 and 9 (Table 16) equal —1.46 and 1.22, respectively. [Pg.203]

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