Liquid with memory

Papaiiastasiou, T. C., Scriven, L. E. and Macoski, C. W., 1987. A finite element method for liquid with memory. J. Non-Newtonian Fluid Mech 22, 271-288. 

Constitutive equations for the Rouse and Zimm models have been derived, and are found to be expressible in the form of Lodge s elastic liquid equation [Eq.(6.15)], with memory function given by (101) ... 

Useful applications have been found lor the varied effects of these crystal changes. One of the first came from the properly of selectively reflecting visible light because this is lempcraiurv-dependent. the property can be used as a temperature detector, and in gel lurm liquid crystals have been used lor the early detection of those cancers which cause hot spots in the body. Applications of the smectic modifications arise from their ferroelectric properties this phase can function as a fast-switching light-valve device with memory. This kind of application requires some... 

These coefficients, along with the shear viscosity rj = cyii/y, often approach constant values at low shear rates these are called the zero-shear values, rjo, 4>i,o, and 4 2,o- Figure 1-9 shows for a polyethylene melt that the zero-shear constant values of rj r]o and 4 1 — 4/1,0 are approached at low shear rates. For a viscoelastic simple liquid with fading memory, the zero-shear values of the viscosity and first normal stress coefficient are related to the zero-frequency values of the dynamic moduli by... 

At low shear rates, a viscoelastic simple liquid with fading memory satisfies the constitutive equation of a Newtonian liquid, that is,... 

Note If the material consists of a solid matrix interspersed with a continuous liquid—as is the case for most gels—deformation will always lead to flow of the liquid with respect to the matrix. This causes frictional energy dissipation, hence a finite value of G" and a finite tan 8. Nevertheless, the system may have a perfect memory, i.e., a response like that in Figure 5.8b. In other words, such a matrix may be called viscoelastic without showing any flow. To be sure, many gels do show some flow upon applying a stress. 

Application of mean-field theories to interfacially constrained and size-limited polymer systems failed to describe the rather unexpected mesoscale behavior observed experimentally. The extension of the interfacial boundary far into the bulk is unexpected because many amorphous polymer systems are theoretically well treated as van der Waals liquids with an interaction length on the order of the radius of gyration, i.e., the effective molecular size. At solid interfaces the radius of gyration is further compressed, like a pancake, and thus, any memory effects of the... 

Answer An electronic temperature monitor could be equipped with a bar-code liquid crystal display which could be read by a portable bar-code reader. These devices have a memory so several readings may be taken before they are readout over a telephone modem to a data logging computer. The simplest way to read the acid type would be to post a label that is bar-coded to indicate the acid type. Tire acid quantity could be indicated by an acid level gage using a bar-code display of the level. The aluminum quality could be indicated by displaying a label in bar-code. The amount of aluminum could be determined by weight using a bar-code readout on the scales. 

The function iKt-t ) may be interpreted as a memory function having a form as shown in Figure 3.14. For an elastic solid, iff has the value unity at all times, while for a purely viscous liquid iff has the value unity at thfe current time but zero at all other times. Thus, a solid behaves as if it remembers the whole of its deformation history, while a purely viscous liquid responds only to its instantaneous deformation rate and is uninfluenced by its history. The viscoelastic fluid is intermediate, behaving as if it had a memory that fades exponentially with time. The purely elastic solid and the purely viscous fluid are just extreme cases of viscoelastic behaviour. 

Apparently, the formation of the microporous structure within the PVdF—HFP copolymer was of critical importance to the success of Bellcore technology, and the ion conductivity was proportional to the uptake of the liquid electrolyte. To achieve the desired porosity of PVdF film, Bellcore researchers prepared the initial polymer blend of PVdF with a plasticizer dibutylphthalate (DBP), which was then extracted by low boiling solvents after film formation. Thus, a pore-memory would be left by the voids that were previously occupied by DBP. However, due to the incomplete dissolution of such high-melting DBP during the extraction process, the pore-memory could never be restored at 100% efficiency. Beside the total volume of pores thus created by the plasticizer. 

Alkylimidazolinm tetraflnoroborates are, for example, ionic liquids at room-temperature that can provide an anion to stabilize an intermediate cation-radical with no possibility of nucleophilic attack on it. Ionic liquids have a huge memory effect, and their total friction is greater than that of conventional polar solvents. Thus, the total friction of l-ethyl-3-methylimidazolium hexafluoro-phosphate is about 50 times greater than that of AN (Shim et al. 2007). The solvent effects of ionic liquids on ion-radical ring closures deserve a special investigation. The ring closure reactions can be, in principal, controlled by solvent effects. 

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