Viscosity relationship

Rheology. Flow properties of latices are important during processing and in many latex appHcations such as dipped goods, paint, inks (qv), and fabric coatings. For dilute, nonionic latices, the relative latex viscosity is a power—law expansion of the particle volume fraction. The terms in the expansion account for flow around the particles and particle—particle interactions. For ionic latices, electrostatic contributions to the flow around the diffuse double layer and enhanced particle—particle interactions must be considered (92). A relative viscosity relationship for concentrated latices was first presented in 1972 (93). A review of empirical relative viscosity models is available (92). In practice, latex viscosity measurements are carried out with rotational viscometers (see Rpleologicalmeasurement). 

With the widespread use of software packages to assist with computational fluid dynamics (CFD) of polymer flow situations, other types of viscosity relationships are also used. For example, the regression equation of Klien takes the form... 

Heat transfer can, of course, be increased by increasing the agitator speed. An increase in speed by 10 will increase the relative heat transfer by 10. The relative power input, however, will increase by 10In viscous systems, therefore, one rapidly reaches the speed of maximum net heat removal beyond which the power input into the batch increases faster than the rate of heat removal out of the batch. In polymerization systems, the practical optimum will be significantly below this speed. The relative decrease in heat transfer coefficient for anchor and turbine agitated systems is shown in Fig. 9 as a function of conversion in polystyrene this was calculated from the previous viscosity relationships. Note that the relative heat transfer coefficient falls off less rapidly with the anchor than with the turbine. The relative heat transfer coefficient falls off very little for the anchor at low Reynolds numbers however, this means a relatively small decrease in ah already low heat transfer coefficient in the laminar region. In the regions where a turbine is effective,... 

Figure 9. Relative heat transfer coefficient vs. percent polystyrene solids hosed on viscosity relationship shown in Figure 8...

Stepwise condensation polymerizations can be modeled as a second-order reaction of the functional groups. Let a be the concentration of functional groups so that = —ka - The following viscosity relationship... 

To a better approximation (see Chap. XIV), the volume of the cloud goes as a being the exponent in the intrinsic viscosity relationship Eq. 

A similar variety of samples was tested for thermal stability by capillary rheometry and TGA. Figure 6.3 shows the viscosity-shear rate dependence for PCTFE homopolymers and one copolymer (Alcon 3000). All materials, save one, showed virtually identical viscosity relationships despite large changes in inherent viscosity. Only the polymers from runs initiated by fluorochemical peroxides (FCP) showed a dependence of molecular weight (as measured by inherent viscosity) upon melt viscosity. 

Borman, W. F. H., Molecular weight-viscosity relationships for polybutylene terephthalate,./. Appl. Polym. Sci., 22, 2119-2126 (1978). 

Two new LDPE resins are proposed to be processed on a similar extruder as described in the example in Section 1.5.1. The extruder here is configured with a downstream gear pump such that the discharge pressure for the extruder is targeted at 7 MPa. The resin manufacturer has provided viscosity data in the form of a viscosity relationship ... 

For most solutions, Equation 3.31 reduces to the Huggins viscosity relationship, Equation 3.32 ... 

What are general typical values for a in the viscosity relationship to molecular weight ... 

In suspensions of particles with an aspect ratio (length to diameter) greater than 1, particle rotation during flow results in a large effective hydrodynamic volume, and Kh > 2.5 (see Figure 4.7). At particle volume fractions above about 5-10%, interaction between particles during flow causes the viscosity relationship to deviate from the Einstein equation. In such instances, the reduced viscosity is better described by the following relationship ... 

Woodman, A. L., W. J. Murbach, and M. H. Kaufman, Vapor Pressure and Viscosity Relationships fora Homologous Series of a, a -Dinitriles. J. Phys. Chem., 1960 64, 658-660. 

Hydrodynamic chromatography was originally described by Small (7) in 1974. A number of publications have appeared since then which describe the separation mechanism and sample detection methods used with HDC (5, 8-18). In addition, Van Gilder, et. al. (19) used HDC as the primary particle sizing technique in research on the particle size versus viscosity relationship of high solids paper coating latices. 

F 2 Fee, J. G., W. S. Port and L. P. Witnauer Molecular weight viscosity relationship of gamma-irradiated octadecyl vinyl ether and octadecyl methacrylate. J. Polymer Sci. 33, 95 (1958). 

T 8 — Molecular weight-intrinsic viscosity relationship and molecular weight distribution of low pressure polyethylenes. J. Polymer Sci. 24,333 (1957). 

S. Gratch and S. Loshaek Viscosity relationships for polymers in bulk and concentrated solutions, p. 431—493 dans "Rheology . Ed. F. R. Eirich, Vol. 1, New-York Academic Press 1956. 

L6. Longworth, R., and W. F. Bdsse Melt-viscosity relationships for molten polyethylene-paraffin wax mixtures. Trans. Soc. Rheol. 6, 179—196 (1962). 

Emulsions of these resins with relatively high solids content can be prepared while the corresponding solvent cuts have viscosities too high for use in coatings. For example, at 40% solids in Cellosolve acetate, ARALDITE 488 has a viscosity of 6000 cP. while the water-borne emulsion at the same solids level is only 1000 cP. For most methods of application the solids content of the solvent cut would have to be dropped below 40% to give a workable viscosity and this would exclude the resin from some important end uses such as can end and 3-piece can body coatings. The resin in its emulsified form, however, has the proper solids/viscosity relationship for this particular end use. 

In any determination of the pour point, petroleum that contains wax produces an irregular flow behavior when the wax begins to separate. Such petroleum possesses viscosity relationships that are difficult to predict in pipeline operation. In addition, some waxy petroleum is sensitive to heat treatment that can also affect the viscosity characteristics. This complex behavior limits the value of viscosity and pour point tests on waxy petroleum. However, laboratory pumpabUity tests (ASTM D-3245, IP 230) are available that give an estimate of minimum handling temperature and minimum line or storage temperature. 

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