Interfaeial properties

Hodkin EN, Nieholas MG (1973) Snrfaee and interfaeial properties of stoiehiometric uranium dioxide. J Nuelear Mater 47 23-30... 

Further details of interfaeial rheology of crude-oil emulsion films are diseussed extensively by Menon et al. (174), Neustadter et al. (166), Mohammed et al. (175), Tambe et al. (176), and Mukherjee and Kushnick (167). They discussed the effects of demulsi-fiers on the interfaeial properties governing the crude-oil demulsification. 

Floes are elusters of partieles that are usually present in liquid suspensions. The elusters are formed when partieles are held together through weak forees, sueh as eleetrostatie forees or bounding of organie polymers. As a result, these partieles ean be easily separated or redispersed by appropriately modifying the interfaeial properties, so that the weak foree interaction disappears. The presence of floes will decrease the packing homogeneity of the consolidated body and thus is undesirable. 

These remarks, whieh arc trivial for every reader, widi even a minimal experienee in working with solvents, have been added here to justify our ehoiee of not trying to give a schematic overview, and also to justify die extremely sehematie presentation of the unique speeifie more advanced subj ect we shall here eonsider, the interfaeial properties of hquids. 8.9.1 THE BASIC TYPES OF LIQUID SURFACES... 

Chapter 4 then expands the diseussion on the use of nanoparticles in membrane modification processes. Materials in the form of nanoparticles have a large surface area to volume ratio, which infers many interesting properties on nanoparticulate systems due to the involved interfaeial properties. As a consequence, nanoparticles are currently receiving a lot of interest in many industries, such as membrane technology where the control of interfacial interactions is important. Nanoparticles affect the permeability, selectivity, hydrophilicity, thermal and electrical conductivities, mechanical strength, thermal stability, and the antiviral and antibacterial properties of the polymeric membranes. Chapter 4 discusses important examples of... 

Jana, S., Singh, J. K., and Kwak, S. K. 2009. J. Chem. Phys. Vapor-liquid eritieal and interfaeial properties of square-well fluids in slit pores. 130 214707. 

This form is partieularly appropriate when the gas is of low solubility in the liquid and "liquid film resistanee" eontrols the rate of transfer. More eomplex forms whieh use an overall mass transfer eoeffieient whieh ineludes the effeets of gas film resistanee must be used otherwise. Also, if ehemieal reaetions are involved, they are not rate limiting. The approaeh given here, however, illustrates the required ealeulation steps. The nature of the mixing or agitation primarily affeets the interfaeial area per unit volume, a. The liquid phase mass transfer eoeffieient, kL, is primarily a funetion of the physieal properties of the fluid. The interfaeial area is determined by the size of the gas bubbles formed and how long they remain in the mixing vessel. The size of the bubbles is normally expressed in terms of their Sauter mean diameter, dj, whieh is defined below. How long the bubbles remain is expressed in terms of gas hold-up, H, the fraetion of the total fluid volume (gas plus liquid) whieh is oeeupied by gas bubbles. 

Most simulations have been performed in the mieroeanonieal, eanonieal, or NPT ensemble with a fixed number of moleeules. These systems typieally require an iterative adjustment proeess until one part of the system exhibits the required properties, like, eg., the bulk density of water under ambient eonditions. Systems whieh are equilibrated earefully in sueh a fashion yield valuable insight into the physieal and, in some eases, ehemieal properties of the materials under study. However, the speeifieation of volume or pressure is at varianee with the usual experimental eonditions where eontrol over the eomposition of the interfaeial region is usually exerted through the ehemieal potential, i.e., the interfaeial system is in thermodynamie and ehemieal equilibrium with an extended bulk phase. Sueh systems are best simulated in the grand eanonieal ensemble where partiele numbers are allowed to fluetuate. Only a few simulations of aqueous interfaees have been performed to date in this ensemble, but this teehnique will undoubtedly beeome more important in the future. Partieularly the amount of solvent and/or solute in random disordered or in ordered porous media ean hardly be estimated by a judieious equilibration proeedure. Chemieal potential eontrol is mandatory for the simulation of these systems. We will eertainly see many applieations in the near future. 

Movements in the plane of the interface result from local variations of interfacial tension during the course of mass transfer. These variations may be produced by local variations of any quantity which affects the interfacial tension. Interfaeial motions have been ascribed to variations in interfacial concentration (H6, P6, S33), temperature (A9, P6), and electrical properties (AlO, B19). In ternary systems, variations in concentration are the major factor causing interfacial motion in partially miscible binary systems, interfacial temperature variations due to heat of solution effects are usually the cause. 

Surfaee/interfacial tension is a well-defined thermodynamic property (131). It is the energy required to display a unit new interfaeial area. From classical Gibbsian thermodynamics, the various modes of energy transfer between the system and the surroundings ean be formulated by a relation called a fundamental equation the fundamental equation (131, 132) of an interface between two bulk phases is given by... 

There are four rheologieal parameters which describe the response to imposed interfaeial stresses or deformation. For a Newtonian interfaee, the signifieant rheological properties that determine interfaeial motion are the interfacial shear viscosity, the interfaeial dilational viscosity, and the interfaeial tension gradient. The interfaeial shear elasticity, e and viscosity, describe the resistance of the... 

Emulsification and demulsification are both eomplex processes. However, as noted earlier, demulsifieation is by no means the opposite of emulsification (200,201). This is especially the case in the petroleum industry. In order to demulsify a crude W/O emulsion efficiently, it has been emphasized that it is advantageous to understand first the characteristics of the emulsions, the nature of interfaeial films, and hence the causes of stability. Accordingly, in choosing a demulsification protocol, one would first identify key factors responsible for the stabihty, find the target properties to modify toward destabilization, introduce sufficient energy to promote coalescence, and find the best conditions to allow phase separation. 

The naturally biodegradable polymers such as starch, chitosan and cellulose derived from natural sources have produced a number of interesting NR blends and IPNs. These blended systems have an advantage in that they create fewer waste disposal problems compared to the petroleum based polymeric materials. The use of stareh blends to enhance the biodegradability of conventional plastics has been reported by many researchers in order to reduce the environmental impaet of petroleum based plastic products and waste. The NR/maize stareh blends exhibited a decrease in their mechanical strength due to the speeifie properties of starch. However, the blended polymers showed a low interfaeial interaetion between the two phases due to the different polarity behaviour of the hydrophobic NR and the hydrophilic starch. 

Thus, the obtained in the present work results have shown that the nanotubes geometry, characterized by their length, diameter and ring-like structures radius, is nanocomposites polymer/CNT specific feature. This factor plays a crucial role in the interfaeial adhesion polymer matrix - nanofiller level determination and, as consequence, in polymer nanocomposites, filled with CNT, mechanical properties formation. 

Some studies investigated changes in room temperature mechanical properties with eompatibilization however some studies were interested primarily in rheologieal behavior. The addition of compatibilizer raises G at low frequeneies , reduces interfaeial tension and inereases the steady-shear melt viseosity. "... 

It is well known that the mechanical properties of fiber-reinforced composites are highly dependent on the interactions between the fiber and the matrix. The primary role of the interface in composites is to transfer the load from the matrix to the fibers. To take full advantage of the mechanical properties of the fiber and matrix, the interfaeial shear strength between the fiber and matrix must be greater than the failure shear strength of the matrix or of the fiber. Several mechanisms that contribute to adhesion have been identified, namely, mechanical, physical interaction, and chemical bonding at the fiber-matrix interface. 

A wide range of analytical techniques were used to analyze the effects of the fiber surface modification on the performance of the composites. Average maximum interfaeial shear strength values greater than the maximum shear strength of the matrix were found to exist for some surface modified fiber composites. This was due to the presence of an interphase called the transcrystalline region which had greater mechanical properties than that of the matrix bulk material. 

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