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Spriggs model

The dynamic functions that conform to the Spriggs model are e]q>ressed as follows ... [Pg.82]

Thus, it is obvious that the dynamic and steady-state characteristics of a polymeric melt could be equivalent when appropriately shifted by an amount c relative to each other. Note that only in the case of e = —1 and hence c = 1 does the Spriggs model predict a correlation at -y = to. [Pg.195]

Figure 3.3 gives logarithmic plots of n/r] versus predicted from three models (1) the ZFD model, (2) the Oldroyd three-constant model, and (3) the Spriggs model. It is seen in Figure 3.3 that the predicted viscosities from all three models decrease at a much faster rate than those observed experimentally (see Figure 3.2) with increasing shear rate, and that the viscosities predicted from the Oldroyd three-constant model level off as shear rate is increased, which is seldom observed experimentally. [Pg.68]

Figure 3.5 Comparison of log versus y plot (O) and log j versus y plot ( ) for a commercial polystyrene at 200 °C with the predictions of the Spriggs model, Eq. (3.38), with r]Q = 3.1 X 10 Pa-s, X = 1.90 s, a = 2.78, and c = 0.816. The data at y < 6 s were obtained using the cone-and-plate fixture of a rotational-type rheometer and the data at y > 10 s" were obtained using a continuous-flow capillary rheometer. Refer to Chapter 5 for details of the experimental methods employed to obtain the data. Figure 3.5 Comparison of log versus y plot (O) and log j versus y plot ( ) for a commercial polystyrene at 200 °C with the predictions of the Spriggs model, Eq. (3.38), with r]Q = 3.1 X 10 Pa-s, X = 1.90 s, a = 2.78, and c = 0.816. The data at y < 6 s were obtained using the cone-and-plate fixture of a rotational-type rheometer and the data at y > 10 s" were obtained using a continuous-flow capillary rheometer. Refer to Chapter 5 for details of the experimental methods employed to obtain the data.
Figure 6.6 Plots of relaxation time X versus the reciprocal of absolute temperature T for (O) LDPE (Rexene 111), (A) LDPE (PE 510), ( ) LDPE (NPE 962), (V) polypropylene (Profax 6423), and (O) polystyrene (Styron 678), where the values of X, appearing in Eq. (3.39), were determined by curve fitting the experimentally obtained log versus log y plot to the theoretical prediction of the Spriggs model, Eq. (3.38). Figure 6.6 Plots of relaxation time X versus the reciprocal of absolute temperature T for (O) LDPE (Rexene 111), (A) LDPE (PE 510), ( ) LDPE (NPE 962), (V) polypropylene (Profax 6423), and (O) polystyrene (Styron 678), where the values of X, appearing in Eq. (3.39), were determined by curve fitting the experimentally obtained log versus log y plot to the theoretical prediction of the Spriggs model, Eq. (3.38).
In the shear range of polymer processing the power law is a good approximation, but not in the low shear rate range. For this reason a better approximation is Spriggs truncated power law model law (Spriggs, 1965) ... [Pg.546]

Perkins, J. D., and Barton, G. W., Modelling and simulation in process operation. In Foundations of Computer-Aided Process Operations (G. V. Reklaitis and H. D. Spriggs, eds.). CACHE Corp., Austin, TX, and Elsevier, New York, 1987. [Pg.255]

A number of models have been developed to describe transient viscoelastic behavior and one must have at hand carefully obtained rheological data in order to test the applicability of the models. Another example of the applicability of models to viscoelastic data is the study of Leppard and Christiansen (1975) in which the models proposed by Bogue and Chen, Carreau, and Spriggs were evaluated. In the case of foods, the empirical models have been developed to describe the transient data on stick butter, tub margarine (Mason et al, 1982), canned frosting (Kokini and Dickie, 1981 Dickie and Kokini, 1982), and mayonnaise (Campanella and Peleg, 1987c). [Pg.17]

The KSR and Rouse models were subj ected to numerous experimental tests. A reasonably good agreement between the theoretical predictions and experimental data was demonstrated for a variety of dilute polymeric solutions. Further advance in the molecular-kinetic approach to description of relaxation processes in polymeric systems have brought about more sophisticated models. They improve the classical results by taking into account additional factors and/or considering diverse frequency, temperature, and concentration ranges, etc. For the aims of computer simulation of the polymeric liquid dynamics in hydrodynamic problems, either simple approximations of the spectrum, Fi(A), or the model of subchains are usually used. Spriggs law is the most used approximation... [Pg.362]

Spriggs, T. W., Afour constant model for viscoelastic fluids. Chem. Eng. Sd, 20, 931-946 (19. ... [Pg.92]


See other pages where Spriggs model is mentioned: [Pg.82]    [Pg.83]    [Pg.194]    [Pg.82]    [Pg.83]    [Pg.194]    [Pg.59]    [Pg.68]    [Pg.68]    [Pg.68]    [Pg.69]    [Pg.210]    [Pg.82]    [Pg.83]    [Pg.194]    [Pg.82]    [Pg.83]    [Pg.194]    [Pg.59]    [Pg.68]    [Pg.68]    [Pg.68]    [Pg.69]    [Pg.210]    [Pg.156]    [Pg.178]    [Pg.1002]    [Pg.121]    [Pg.107]    [Pg.300]    [Pg.156]    [Pg.528]    [Pg.194]    [Pg.194]    [Pg.201]    [Pg.92]    [Pg.194]    [Pg.194]    [Pg.201]   
See also in sourсe #XX -- [ Pg.194 ]

See also in sourсe #XX -- [ Pg.194 ]

See also in sourсe #XX -- [ Pg.59 ]




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