Pseudo-plastic liquids

This procedure can be repeated for different values of N. A compilation of the experimental values of ks for a variety of impellers, turbine, propeller, paddle, anchor, and so on, has been given by Skelland(16), and an examination of Table 7.1 suggesLs that for pseudo-plastic liquids, ks lies approximately in the range of 10-13 for most configurations of practical interest/22 231 SKELLAND l6) has also correlated much of the data on the agitation of purely viscous non-Newtonian fluids, and this is shown in Figure 7.8. 

Study of the flow curves shows that emulsions with a low content of dispersed phase (< )< 0.1) appear to be Newtonian fluids. As the dispersed phase content increases (< ) > 0.1), the extracting emulsion becomes a non-Newtonian, pseudo-plastic liquid. 

Figure 12-5. Flow curves for plastic and pseudo-plastic liquids.

Nagata, S., M. Nishikawa, H. Tada, and S. Gotoh (1971). Power consumption of mixing impellers in pseudo-plastic liquids, J. Chem. Eng. Jpn., 4, 72-76. 

J. Todorovic, D.M. Krstic, G.N. Vatai, M.N. Tekic, Gas absorption in a hoUow-fiber membrane contactor with pseudo-plastic liquid as an absorbent, Desalination 193... 

Irrespective of the plasticizer type and amount, melted TPSs exhibit non-Newtonian flow behavior typical of pseudo-plastic liquids. Increasing plasticizer content causes decreasing viscosity, as a result of which TPS materials flowing capacities increase. Thermoplastic starch shows a clear relationship between viscosity and temperature, also a well-known effect in the case of conventional polymers [8, 12, 26, 31, 32, 55]. 

The melt flow under isothermal conditions, when it is described by the rheological equation for the Newtonian or power law liquid, has been studied in detail63 66). The flow of the non-Newtonian liquid in the channels of non-round cross section for the liquid obeying the Sutterby equation have also been studied 67). In particular, the flow in the channels of rectangular and trigonal cross section was studied. In the analysis of the non-isothermal flow, attention should be paid to the analysis 68) of pseudo-plastic Bingham media. 

Solyom and Ekwall (20) have studied rheology of the various pure liquid crystalline phases in the sodium caprylate-decanol-water system at 20 °C, for which a detailed phase diagram is available. Their experiments using a cone-and-plate viscometer show that, in general, apparent viscosity decreases with increasing shear rate (pseudo-plastic behavior). Values of apparent viscosity were a few poise for the lamellar phase (platelike micelles alternating with thin water layers), 10-20 poise for the reverse hexagonal phase (parallel cylindrical micelles with polar... 

The term viscosity, as used above, is not accurate. Dense media at higher solid concentrations exhibit characteristics of non-Newtonian liquids, namely, Bingham plastic or pseudo-plastic behavior, as shown in Fig. 14. ... 

This studies have shown that the rheological parameters are affected by the type of measuring device, composition of the paste and rheological history of the sample. The pastes can be attributed to the Newtonian or non-Newtonian types of liquid between the later the plastic (Bingham), pseudo-plastic or exhibiting the dilatancy phenomena can be differentiated. Moreover, the pastes reveal basically the thixotropy or anti-thixotropy properties. 

Deviations from Newtonian flow can occur when shear stress does not increase in direct proportion to shear rate. Such deviation may be in the direction of thickening (called dilatent flow) and in the direction of thinning (called pseudo plastic). Related to non-Newtonian flow is the behavior of thixotropic liquids when subjected to shear, as explained above. Flow behavior can be represented by the following equation ... 

Total height of the holding vessel including 40% excess volume (m) Height of tapered portion of the primary fluid nozzle (m) Consistency index for pseudo-plastic non-Newtonian liquid (Pa s") First-order reaction rate constant (m /kg catalyst s)... 

Flow behavior index for pseudo-plastic non-Newtonian liquid (—) Number of orifices in a given multiorifice nozzle (—)... 

Bhutada SR, Pangarkar VG. (1989b) Gas induction and hold-up characteristics of liquid jet loop reactors pseudo plastic non-Newtonian liquids. Chem. Eng. Sci., 43 2904-2907. Bhutada SR, Pangarkar VG. (1989) Solid suspension and mixing in liquid jet loop reactors. Chem. Eng. Sci., 44 2384-2387. 

Table 11 shows that a plasticizer is most effective when its solubility or polarity matches that of the rubber in which it is being used. This is taken to be a true solvating effect and not a pseudo-plasticization obtained by diluting the polymer with a large volume of incompatible liquid. The further apart any two types of rubber are in solubility parameter or viscosity, the more difficult it is to achieve compatibility. Blends of plasticizers, each compatible with different rubbers being... 

A theoretical idealisation of pseudo-plastic with yield value behaviour is the Bingham plastic (see curve 3 of Fig. 6.3), which deforms elastically until the yield stress Ty is reached and then flows like a Newtonian liquid with 7 linearly related to t. When r is greater than Ty ... 

Four fractions of pseudo-compounds are obtained by solution analysis of crude oil residue or its cracked product. During solution analysis of the cracking product from thermal treatment of vacuum residue or mixtures of vacuum residue and plastics (such mixtures were used in our investigation), a first step of solution analysis is soxhlet extraction. In the soxhlet extractor, the liquid/solid product is extracted with fresh warm solvent (THF) that does not contain the extract. This can increase the extraction rate, as the sample is contacting fresh warm solvent. The sample is placed inside a cellulose thimble and placed in the extractor. The extractor is connected to a flask containing the extraction solvent, and a condenser is connected above the extractor. The solvent is boiled, and the extractor has a bypass arm that the vapor passes through to reach the condenser, where it condenses and drips into the sample in the thimble. Once the solvent reaches the top of the siphon arm, the solvent and extract are siphoned back into the lower flask. The solvent reboils, and the cycle is repeated until the sample is completely extracted, and the extract is in the lower flask. 

It is possible to think of yield and plastic deformation in polymers as a type of viscous flow, especially since glassy polymers.are basically frozen liquids that have failed to crystallize. Eyring developed a theory to describe viscous flow in liquids and it can be readily adapted to describe the behaviour of glassy polymers. The segments of the polymer chain can be thought of as being in a pseudo-lattice and for flow to occur a segment must move to an adjacent site. There will be a potential barrier to overcome,... 

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