Viscosity number

Dilute Polymer Solutions. The measurement of dilute solution viscosities of polymers is widely used for polymer characterization. Very low concentrations reduce intermolecular interactions and allow measurement of polymer—solvent interactions. These measurements ate usually made in capillary viscometers, some of which have provisions for direct dilution of the polymer solution. The key viscosity parameter for polymer characterization is the limiting viscosity number or intrinsic viscosity, [Tj]. It is calculated by extrapolation of the viscosity number (reduced viscosity) or the logarithmic viscosity number (inherent viscosity) to zero concentration. 

The viscosity ratio or relative viscosity, Tj p is the ratio of the viscosity of the polymer solution to the viscosity of the pure solvent. In capillary viscometer measurements, the relative viscosity (dimensionless) is the ratio of the flow time for the solution t to the flow time for the solvent /q (Table 2). The specific (sp) viscosity (dimensionless) is also defined in Table 2, as is the viscosity number or reduced (red) viscosity, which has the units of cubic meters per kilogram (m /kg) or deciUters per gram (dL/g). The logarithmic viscosity number or inherent (inh) viscosity likewise has the units m /kg or dL/g. For Tj g and Tj p, the concentration of polymer, is expressed in convenient units, traditionally g/100 cm but kg/m in SI units. The viscosity number and logarithmic viscosity number vary with concentration, but each can be extrapolated (Fig. 9) to zero concentration to give the limiting viscosity number (intrinsic viscosity) (Table 2). 

Fig. 9. Plots of viscosity number (/c) and the logarithmic viscosity number (/c) vs concentration. Extrapolations to 2ero concentration...

The relative viscosity of a dilute dispersion of rigid spherical particles is given by = 1 + ft0, where a is equal to [Tj], the limiting viscosity number (intrinsic viscosity) in terms of volume concentration, and ( ) is the volume fraction. Einstein has shown that, provided that the particle concentration is low enough and certain other conditions are met, [77] = 2.5, and the viscosity equation is then = 1 + 2.50. This expression is usually called the Einstein equation. 

This equation is based on the approximation that the penetration is 800 at the softening point, but the approximation fails appreciably when a complex flow is present (80,81). However, the penetration index has been, and continues to be, used for the general characteristics of asphalt for example asphalts with a P/less than —2 are considered to be the pitch type, from —2 to +2, the sol type, and above +2, the gel or blown type (2). Other empirical relations that have been used to express the rheological-temperature relation are fluidity factor a Furol viscosity P, at 135°C and penetration P, at 25°C, relation of (H—P)P/100 and penetration viscosity number PVN again relating the penetration at 25°C and kinematic viscosity at 135 °C (82,83). 

ISO viscosity number. Table 12.1 compares typical correlations between number and weight average molecular weights with ISO numbers, AT-values and ASTM viscosity measurements. 

Average molecular weight ISOIR174- 1961(E) viscosity number K-value ASTM DI243-58T ... 

Viskositats-messer, m. viscosimeter, viscometer. -zahl,/. viscosity number or value. Vistra. Viatra (an acetate rayon). T.N. visuell, a. visual. 

Viscosity, intrinsic Also called limiting viscosity number. For a plastic, it is the limiting value of an infinite dilution. It is the ratio of the specific viscosity of the plastic solution to its concentration in moles per liter. 

Some of the results of bulk polymerization of 61 by using different anionic catalysts are summarized in Table 858 It was easily polymerized in the presence of alkali metal compounds above 60 °C. The polymerization at 150 °C was too fast to be controlled. The yield and the viscosity number, i gp/c, of the resulting polyamide increased with the reaction time. The initial rate of the polymerization became higher with the size of the countercation, in analogy to the case of anionic polymerization of e-caprolactam59. The rate increased also with raising temperature as shown in Fig. 658. ... 

Concentrations of the monomer, solvent, polymer, and initiator Solution viscosity Number average polymer mol. wt. Weight average polymer mol. wt. Polymerization Rate Reaction time Heat generated Heat losses Solution Temperature Partial pressures of the monomer, solvent, and nitrogen Total pressure... 

Having obtained the value of the limiting viscosity number, we can calculate relative molar mass using the semi-empirical equation ... 

In the following sections, synthesis of the anionic polymers, copolymer molecular weight, limiting viscosity number, electrolyte effects, solution shear thinning, screen factor, polymer radius of gyration, and solution aging will be discussed and data on the copolymers presented. 

Assays. Nitrogen assays to determine 1-amidoethylene unit content were done by Kjeldahl method. Limiting viscosity numbers were determined from 4 or more viscosity measurements made on a Cannon-Fenske capillary viscometer at 30°C. Data was extrapolated to 0 g/dL polymer concentration using the Huggins equation(44) for nonionic polymers and the Fuoss equation(45) for polyelectrolytes. Equipment. Viscosities were measured using Cannon-Fenske capillary viscometers and a Brookfield LV Microvis, cone and plate viscometer with a CP-40, 0.8° cone. Capillary viscometers received 10 mL of a sample for testing while the cone and plate viscometer received 0.50 mL. 

Limiting Viscosity Number. Limiting viscosity numbers for the polymers in distilled water are given in Table 3 Limiting viscosity number increases with increasing copolymer molecular weight. 

Further, after 12 to 14 percent hydrolysis, limiting viscosity number of the derived, partially-hydrolyzed copolymer is 3 to 10 times larger than that of its nonionic precursor. The ratio of [n] after... 

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