Dilute solution viscosity measurements

IL. Dilute solution viscosity measurements were done at 30 with the appropriate Ostwald-Fenske capillary viscometers. The water content of all organic solvents, used as the liquid phase in solid-liquid PTC runs was analyzed by potentiometric Karl Fischer titration using a Metrohm AG CH 9100 model automatic titrator. 

The dilute solution viscosity measurement is applicable to all polymers that dissolve to give stable solutions at temperatures close to the boiling point of the solvent. 

This equation will be derived in Chapter 8. Dilute solution viscosity measurements are important characterization tools for polymers because... 

The dilute solution viscosity measurements were conducted using Ubbelohde viscometers generally conducted at 25 + 0.05°C in a thermo-stated bath. The reduced viscosity or viscosity number [defined as (t -ri0)/ri0c, where 0 is the viscosity of the polymer solution, 0o is the viscosity of the solvent (or mixed solvent), and c is the concentration of polymer in g/100 mL] was calculated for each solution measured. 

A step-growth polycondensation route has been succesfully devised to prepare novel nickel polymers 207 with arene spacer groups. The procedure involved the polycondensation of the fluorinated dilithiated species 206 and an Ni(ii) complex (Equation (75))." " The rod-like structure of these polymers was established by dilute-solution viscosity measurements, and the results were similar to those reported for the related platinum polyyne polymers 166 (M = Pt(P Bu3)2 x = 2) (Section 12.06.5.2.3). 

Dilute solution viscosity measurements were made using a Can-non-Fenske viscometer. Number average molecular weight (Mn) and weight average molecular weight (Mw) were calculated from viscosity measurements and the Mark-Houwlnk Constants (12). Gel content was determined by a modification of procedure ASTM D3616. 

Low intrinsic viscosities and high ku values were determined by dilute solution viscosity measurements, indicative of large hydrodynamic interactions supporting the conclusions drawn from LS that intramolecular association does occur at low concentrations. Comparative examination of R and Rh values showed that Rvzwitterionic polymers, which was attributed to dissociation of the aggregates, to some extent, under the applied shear rate in the capillary. Because these forces are generally not very strong, it was concluded that the critical shear rate should be small. Compared to linear cB-fimctionalized polymers, the lower stability of the aggregates formed by the end-functionalized stars was attributed to the steric repulsion of the unfiinctionalized arms. 

Dilute solution viscosity. Dilute solution polymers typically have a dilute solution viscosity greater than 0.1 dL/g. Dilute solution viscosity measurements are used for initial characterization. 

Viscometric Methods.—Dilute Solution Viscosity [ij]. Ubbelohde and Fica automatic viscometers are among the apparatus which are frequently used to obtain thermodjmamic data from dilute solution viscosity measurements. The method suffers from vagaries of interpretation in... 

Inherent viscosity refers to a dilute solution viscosity measurement where it is the ratio of the natural logarithm of the relative viscosity (sometimes called viscosity ratio) to the concentration of the plastic in grams per 100 ml of a solvent solution. 

Viscosity, coefficient It is the shearing stress necessary to induce a unit velocity gradient in a material. In actual measurement, the viscosity coefficient of a material is obtained from the ratio of shearing stress to shearing rate. This assumes the ratio to be constant and independent of the shearing stress, a condition satisfied only by Newtonian fluids. Consequently, in all other cases that includes plastics non-Newtonian), values obtained are apparent and represent one point in the flow chart. Inherent viscosity refers to a dilute solution viscosity measurement where it is the ratio of the natural logarithm of the relative viscosity to the concentration of the plastic in grams per 100 ml of solvent. 

When microgels are colloidally dispersed in a good solvent, they absorb the solvent in the same manner as other crosslinked polymers and swell. The degree of swelling can be determined by particle diameter measurements or volume fi"action determination fi"om dilute solution viscosity measurement [17]. 

This test method is used to determine dilute solution viscosity for all polymers that dissolve completely without chemical reaction or degradation to form solutions that are stable with time at a temperature between ambient and approximately 150°C. The results of the tests are expressed as relative, inherent, or intrinsic viscosity. Reduced and specific viscosity can also be calculated. Table 7-4 shows recommended test conditions for dilute solution viscosity measurements. 

TABLE 7-4. Recommended Test Conditions for Dilute Solution Viscosity Measurements... 

Intrinsic viscosity In dilute solution viscosity measurements, intrinsic viscosity is the limit of the reduced and inherent viscosities as the concentration of the polymeric solute approaches zero and represents the capacity of the polymer to increase viscosity. 

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