Yield value

The yield value of a filled system depends on its filler and the matrix. On 

3 Cochet P, Barruel P. Barriquand L, Grobert J, Bomal Y, Prat E, IRC 93/144th Meeting, Fall 1993. 

Conference Proceedings, Orlando, FI., 26th-29th Oct 1993, Paper 162. 

5 Agarwal S, Campbell G A, Antec 95. Volume I. Conference proceedings, Boston, Ma., 

7 Ishibashi J. Kobayashi A, Yoshikawa T, Shinozaki K, Antec 96. Vol. I. Conference Proceedings, 

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Table 7.16 Fluorescence Spectroscopy of Some Organic Compounds Table 7.17 Fluorescence Quantum Yield Values...

Three replicate determinations are made of the signal for a sample containing an unknown concentration of analyte, yielding values of 29.32, 29.16, and 29.51. Using the regression line from Examples 5.10 and 5.11, determine the analyte s concentration, Ca, and its 95% confidence interval. 

An obvious difficulty here is deciding the location of the broken line portions of the peaks in the region of overlap. Some features of the infrared absorption spectrum may also be analyzed by the same procedure to yield values for 6. 

We shall discuss three types of phenomena for polymer solutions thermodynamic properties in Chap. 8, frictional properties in Chap. 9, and lightscattering properties in Chap. 10. A common feature of virtually all phenomena in these areas is that they all depend on the molecular weight of the solute. Thus observations of these properties can be interpreted to yield values for M we shall use this capability as a unifying theme throughout these chapters. 

Rigid, unsolvated spheres. Stokes law, Eq. (9.5), provides a relationship between f and the radius of the particle. Since this structure is a reasonable model for some protein molecules, experimental D values can be interpreted, via f, to yield values of R for such systems. Note that this application can also yield a value for M, since M = N pj [(4/3)ttR ], where pj is the density of the unsolvated material. 

Another aspect of plasticity is the time dependent progressive deformation under constant load, known as creep. This process occurs when a fiber is loaded above the yield value and continues over several logarithmic decades of time. The extension under fixed load, or creep, is analogous to the relaxation of stress under fixed extension. Stress relaxation is the process whereby the stress that is generated as a result of a deformation is dissipated as a function of time. Both of these time dependent processes are reflections of plastic flow resulting from various molecular motions in the fiber. As a direct consequence of creep and stress relaxation, the shape of a stress—strain curve is in many cases strongly dependent on the rate of deformation, as is illustrated in Figure 6. 

NLGI number ASTM worked penetration, mm /10 at 25°C Approximate yield value. Pa... 

The power law model can be extended by including the yield value r — Tq = / 7 , which is called the Herschel-BulMey model, or by adding the Newtonian limiting viscosity,. The latter is done in the Sisko model, 77 +. These two models, along with the Newtonian, Bingham, and Casson... 

Thixotropy and Other Time Effects. In addition to the nonideal behavior described, many fluids exhibit time-dependent effects. Some fluids increase in viscosity (rheopexy) or decrease in viscosity (thixotropy) with time when sheared at a constant shear rate. These effects can occur in fluids with or without yield values. Rheopexy is a rare phenomenon, but thixotropic fluids are common. Examples of thixotropic materials are starch pastes, gelatin, mayoimaise, drilling muds, and latex paints. The thixotropic effect is shown in Figure 5, where the curves are for a specimen exposed first to increasing and then to decreasing shear rates. Because of the decrease in viscosity with time as weU as shear rate, the up-and-down flow curves do not superimpose. Instead, they form a hysteresis loop, often called a thixotropic loop. Because flow curves for thixotropic or rheopectic Hquids depend on the shear history of the sample, different curves for the same material can be obtained, depending on the experimental procedure. 

Chocolate does not behave as a tme Hquid owing to the presence of cocoa particles and the viscosity control of chocolate is quite compHcated. This non-Newtonian behavior has been described (28). When the square root of the rate of shear is plotted against the square root of shear stress for chocolate, a straight line is produced. With this Casson relationship method (29) two values are obtained, Casson viscosity and Casson yield value, which describe the flow of chocolate. The chocolate industry was slow in adopting the Casson relationship but this method now prevails over the simpler MacMichael viscometer. Instmments such as the Carri-Med Rheometer and the Brookfield and Haake Viscometers are now replacing the MacMichael. 

An equation that yields values of AFF P in units of kj/mol to within about 2% is Chen s equation (1) ... 

The effective surface viscosity is best found by experiment with the system in question, followed by back calculation through Eq. (22-55). From the precursors to Eq. (22-55), such experiments have yielded values of [L, on the order of (dyn-s)/cm for common surfactants in water at room temperature, which agrees with independent measurements [Lemhch, Chem. Eng. ScL, 23, 932 (1968) and Shih and Lem-lich. Am. Inst. Chem. Eng. J., 13, 751 (1967)]. However, the expected high [L, for aqueous solutions of such sldn-forming substances as saponin and albumin was not attained, perhaps because of their non-newtonian surface behavior [Shih and Lemhch, Ind. Eng. Chem. Fun-dam., 10, 254 (1971) andjashnani and Lemlich, y. Colloid Inteiface ScL, 46, 13(1974)]. 

The drermodynamic data for CuaS-FeS (Krivsky and Schuhmann, 1957) show that drese sulphides mix to form approximately ideal ionic liquids. These are molten salts in which the heat of mixing is essentially zero, and die entropy of mixing is related to the ionic fractions of die cations and anions. In the present case die ionic fractions yield values for the activities of the two sulphides... 

Of these terms tlrose involving iron and calcium can be compared as an exatrrple of the exchatrge under ironmaking conditions. Experimental values for tire conesponding equilibria between gas and slag yield values of the sulphide capacities... 

Property of plastics that permits the material to undergo deformation permanently and continuously without rupture from a force that exceeds the yield value of the material. 

Yield value Also called yield stress force necessary to initiate flow in a plastic. 

The ratio of third- to second-order piezoelectric constants has also been determined for x-cut quartz with the acceleration pulse loading method [77G05]. Two experiments yielded values for Cm/Cu of 15.0 and 16.6 compared to the ratio of 15.3 [72G03] determined from the fit to the 25 shock loading experiments. 

For further idtrilihcutiQu car -ophyllenic alcohol was pjorluned iVom it, of which ihi) Uieltin -fioint was found al 06. Two corahuslionfs yielded values correspoiidin j with ibosc- calculai-d (oi ao alcohol C,jE.,0... 

The Br is a measure of the extent to which viscous heating is important relative to an impressed temperature difference. This can be of some concern in the scale-up design, v usually increasing, with other properties remaining constant. A comparison of the Br for a pilot scale (0.05-m screw) and an industrial (0.15-m screw) unit yields values of ca. 0.65, and 5.73, respectively, for the Br with A = 0.5 w/m K and rj = 500 Pa.s at 60 rpm. The numbers suggest that viscous dissipation will be important and will be much more pronounced in the case of an industrial unit. 

The application of Stokes s law to mobilities is a case in point. In Sec. 35 we shall show that, if we compare mobilities of ions in methanol, ethanol, and water, a crude application of Stokes s law yields values that do not even lie in the right order. Nevertheless, when we discuss ionic... 

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