Polymeric fluid

Chandler D 1993 Gaussian field model of fluids with an application to polymeric fluid Phys. Rev. E 48 2989... 

The thermal conductivity of polymeric fluids is very low and hence the main heat transport mechanism in polymer processing flows is convection (i.e. corresponds to very high Peclet numbers the Peclet number is defined as pcUUk which represents the ratio of convective to conductive energy transport). As emphasized before, numerical simulation of convection-dominated transport phenomena by the standard Galerkin method in a fixed (i.e. Eulerian) framework gives unstable and oscillatory results and cannot be used. 

The (CEF) model (see Chapter 1) provides a simple means for obtaining useful results for steady-state viscometric flow of polymeric fluids (Tanner, 1985). In this approach the extra stress in the equation of motion is replaced by explicit relationships in terms of rate of strain components. For example, assuming a zero second normal stress difference for veiy slow flow regimes such relationships arc written as (Mitsoulis et at., 1985)... 

The formulation of calcium chelate materials is based upon the formation of a low-solubiUty chelate between calcium hydroxide and a sahcylate. Dycal utilizes the reaction product of a polyhydric compound and sahcyhc acid. Other sahcyhc acid esters can be similarly used. Vehicles used to carry the calcium hydroxide, extenders, and fillers may include mineral oil, A/-ethyl- -toluenesulfonamide [80-39-7] and polymeric fluids. The filler additions may include titanium dioxide [13463-67-7] zinc oxide, sihca [7631-86-9], calcium sulfate, and barium sulfate [7727-43-7]. Zinc oxide and barium sulfate are useflil as x-ray opacifying agents to ensure a density greater than that of normal tooth stmcture. Resins, rosin, limed rosins, and modified rosins may serve as modifiers of the physical characteristics in both the unset and set states. 

Hill JW, Cuculo JA (1976) In Elongational flow behavior of polymeric fluids, Rev in Macromol Chem 14 B, Marcel Dekker, New York, p 143... 

J. Gulbis, M. T. King, G. W. Hawkins, and H. D. Brannon. Encapsulated breaker for aqueous polymeric fluids. In Proceedings Volume, pages 245-254. 9th SPE Formation Damage Contr Symp (Lafayette, LA, 2/22-2/23), 1990. 

At the molecular level there are several important differences between polymeric fluids and small-molecule fluids. Because of these differences the flow behaviour of polymeric fluids is not similar to that of small-molecule fluids, which are satisfactorily described by Newtonian fluid dynamics. There are several salient features of macromolecular architecture that influence the flow behaviour ... 

In semi-dilute solutions, the Rouse theory fails to predict the relaxation time behaviour of the polymeric fluids. This fact is shown in Fig. 11 where the reduced viscosity is plotted against the product (y-AR). For correctly calculated values of A0 a satisfactory standardisation should be obtained independently of the molar mass and concentration of the sample. 

E. F. Matthys 1988, (Measurement of velocity for polymeric fluids by a photo-chromic flow visualization technique the tubeless siphon), J. Rheol. 32 (8), 773-788. 

The typical viscous behavior for many non-Newtonian fluids (e.g., polymeric fluids, flocculated suspensions, colloids, foams, gels) is illustrated by the curves labeled structural in Figs. 3-5 and 3-6. These fluids exhibit Newtonian behavior at very low and very high shear rates, with shear thinning or pseudoplastic behavior at intermediate shear rates. In some materials this can be attributed to a reversible structure or network that forms in the rest or equilibrium state. When the material is sheared, the structure breaks down, resulting in a shear-dependent (shear thinning) behavior. Some real examples of this type of behavior are shown in Fig. 3-7. These show that structural viscosity behavior is exhibited by fluids as diverse as polymer solutions, blood, latex emulsions, and mud (sediment). Equations (i.e., models) that represent this type of behavior are described below. 

Metzner, A.B. and Metzner, A.P., Stress levels in rapid extensional flow of polymeric fluids, Rheologica Acta 9, No. 2, pp. 174—81 (1970). 

H. C. Ottinger, Stochastic Processes in Polymeric Fluids, Springer, New York, 1996. 

When a spring and a dash pot are connected in series the resulting structure is the simplest mechanical representation of a viscoelastic fluid or Maxwell fluid, as shown in Fig. 3.10(d). When this fluid is stressed due to a strain rate it will elongate as long as the stress is applied. Combining both the Maxwell fluid and Voigt solid models in series gives a better approximation for a polymeric fluid. This model is often referred to as the four-parameter viscoelastic model and is shown in Fig. 3.10(e). Atypical strain response as a function of time for an applied stress for the four-parameter model is found in Fig. 3.12. 

The four-parameter model is very simple and often a reasonable first-order model for polymer crystalline solids and polymeric fluids near the transition temperature. The model requires two spring constants, a viscosity for the fluid component and a viscosity for the solid structured component. The time-dependent creep strain is the summation of the three time-dependent elements (the Voigt element acts as a single time-dependent element) ... 

R. Bird, C. Curtiss, R. Armstrong, and O. Hassager, Dynamics of Polymeric Fluids (Wiley, New York, 1987). 

IV. Configurational Entropy and Characteristic Temperatures for Glass Formation in Polymeric Fluids... 

IV. CONFIGURATIONAL ENTROPY AND CHARACTERISTIC TEMPERATURES FOR GLASS FORMATION IN POLYMERIC FLUIDS... 

There are instances, especially in polymeric fluids, in which 7k is quite distinct from 7b, but... 

Middlemans. Effect of molecular weight distribution on viscosity of polymeric fluids. J. Appl. Polymer. Sci. 11,417-424 (1967). 

In this book we consider only fluids that are isotropic, meaning that the fluid properties are independent of direction. By contrast, solids can readily have spatially oriented properties. Consider, for example, a common material like graphite, whose molecular structure has strongly oriented layers. Both mechanical and thermal properties are vastly different normal to and parallel to the layers. While ordinary fluids exhibit no such properties, it is possible to have anisotropic fluids. For example, long-chain polymeric fluids can exhibit properties that are oriented relative to the flow directions. 

Works published by Brostow (1984) as well as by Kim (1986) seem to indicate that the chemical structure correlates with the stability of a macromolecule in turbulent flow. As mentioned above, the drag reduction of polymeric fluids seems to be linked... 

Metzner AB, Metzner AP (1970) Stress levels in rapid extensional flows of polymeric fluids Rheol Acta 9 174... 

The comparatively less elastic nature of many food products makes the analyses of extensional rheology data easier than has been possible with polymeric fluids. This relative ease of data interpretation provides an opportunity both for learning the extensional behavior of materials and for effective application of extensional rheometry in the food industry. 

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