Low viscosity liquid phase

Mass transfer (the C term), which involves collisions and interactions between molecules, applies differently to both packed and capillary columns. Packed columns are mostly filled with stationary phase so liquid phase diffusion dominates. The mass transfer is minimized by using a small mass of low-viscosity liquid phase. Capillary columns are mostly filled with mobile phase, so mass transfer is important in both the gas and liquid phases. A small mass of low-viscosity liquid phase combined with a low-molecular weight carrier gas will minimize this term. 

Inkjet is a non-contact additive process that delivers metered amounts of a variety of fluids at a precise location in time and space. It requires low viscosity liquid phase inks that must successfully be fired through a nozzle. Inkjet has broad appeal due to its seemingly simple nature. Although all inkjet processes share basic features, the ways in which inkjet technology can be configured are endless. For the most part, drop-on-demand printers have been used in inkjet printing of electronics. ... 

The consequences of the van Deemter equation are that (1) small particles improve the HETP (2) there is an optimum flow rate (3) in general, a high m.w. carrier gas improves the efficiency (4) the smaller the i.d. of the column is, the higher the efficiency (5) the lower the inlet to outlet pressure ratio is, the better the efficiency (6) low vapor pressure, low viscosity liquid phases are best (7) the thinner the stationary phase is, the better and faster the separation ... 

Mixture with a solute. A desired product is often removed by filtration from a reaction mixture. The function of the solvent in this case is to dissolve selectively the impurities (urrreacted raw materials and the outcome of unwanted side reactions) in a low-viscosity liquid phase while having a very low solvent power for the product. 

Typical equipment for low viscosity liquids consists of a vertical cylindrical tank, with a height to diameter ratio of l.5 to 2, fitted with an agitator. For low viscosity liquids, high-speed propellers of diameter about one-third that of the vessel are suitable, running at 10-25 Hz. Although work on single-phase mixing of low viscosity liquids is of limited... 

Apart from the critical impeller speed for solid suspension and efficient gas dispersion, flooding is also a very important phenomenon in three-phase systems. Flooding may take place at low impeller speed or high gassing rate. Under these conditions, the gas is dispersed just around the central shaft of the tank, whereas the solids are settled at the bottom. Flooding characteristics are not affected by particles. Furthermore, high-viscosity liquids are able to handle more gas before flooding than low-viscosity liquids. 

The temperature dependence of the stability of the ass could explain why the ass — jSss transformation takes place at 1350-1700 K [123, 128, 138, 188] in samples with compositions on the boundary of the ass region or in two-phase ass// ss mixtures. The transformation is a solution-reprecipitation process which often is kinetically hindered, and the presence of a liquid or low viscosity glassy phase is necessary [188],... 

Liquid-phase infiltration of preforms has emerged as an extremely useful method for the processing of composite materials. This process involves the use of low-viscosity liquids such as sols, metal- or polymer-melts. Using this infiltration process, it is possible to design new materials with unique microstructures (e.g. graded, multiphase, microporous) and unique thermomechanical properties (graded functions, designed residual strains and thermal shock). 

Kinetics and Phase Behavior - Table IV represents a simplified picture of the situation however, some polymerizations go through several phase changes in the course of the reaction. For example, in the bulk polymerization of PVC, the reaction medium begins as a low viscosity liquid, progresses to a slurry (the PVC polymer, which is insoluble in the monomer, precipitates), becomes a paste as the monomer disappears and finishes as a solid powder. As might be expected, modelling the kinetics of the reaction in such a situation is not a simple exercise. 

The various regimes of low-viscosity liquid which can exist in an agglomerate are depicted in Fig. 2.3. For regular systems of spherical packing, the cohesive forces have been calculated [1,8—10]. These forces originate with the interfacial tension at the liquid surface and the pressure deficiency (suction) created within the liquid phase by curvature at the liquid surface. 

Interest is shown still in the isomerization of stilbene and its derivatives. A study of the pathways for the cis -trans isomerization of 4-nitro, 4,4-dinitro, and 4-nitro-4 -methoxy stilbenes has been reported. The dynamics of the photoisomerization of stilbenes in hydrocarbon solution has been studied and a comparison of the trans -cis isomerization of stilbene in low viscosity liquid alkanes and in the gas phase has been carried out. The photoisomerization of stilbene in straight chain alcohols has provided evidence for the existence of rotational relaxation in the excited and the ground states. An analysis of the isomerization rates of photoexcited stilbene has been made and the photobehaviour of poly deuteriated stilbene has been studied. ... 

If an axially positioned stirrer is operated in a vessel without inserts, the liquid is set in rotation and a vortex is produced. In the case of rapidly rotating stirrers and low viscosity liquids, the vortex can reach the stiner head with the result that the stirrer entrains the gas in the liquid (see section 1.4.5.2). This is generally undesirable because it results in an extraordinarily high mechanical stress on the stirrer shaff, bearings and seal, due to the absence of the liquid bearing . This often leads to the destruction of the stirrer. Even when the vortex formation causes no gas entrainment, rotation of the liquid is always undesirable if a two-phase system with different densities is concerned, since the centrifugal force counteracts the stirring process. 

A further distinction must be made with regard to the degree of imiformity of the liquid phase low viscosity liquids will be much easier to handle than highly viscous paste-like liquids. In this respect the classification of fields of work given in Table 0.1 is recommended. 

If a low-viscosity liquid is beaten to form a foam, it will inevitably become a polyhedral foam. Liquid will always drain from it. For a volume fraction of 0.9, the overrun is 900%, for cp = 0.95, it is even 1900% such a foam would make a very fluffy food. Most aerated foods are different. They are dilute foams in the sense that the bubbles are separate from each other and they remain spherical. To prevent the bubbles from creaming, the continuous phase should have a yield stress. This can be achieved in several manners ... 

The viscosity term shows that it is difficult to disperse a viscous liquid in a low-viscosity continuous phase in this situation there is less shear stress at the drop surface than with drops of low-viscosity liquid, and the viscous drop resists deformation. This equation, however, should not be used for very low values of fii/Hc, since it does not fit the data for the dispersion of gases in liquids. An alternate equation proposed for the dispersion of liquids with six-blade turbines is ... 

An almost irrelevant point of difference in the behavior of foam was whether the discontinuous phase was a gas, a dense gas, or a low-viscosity liquid. The presence of the lamellae across some of the pores gives foam its distinctive properties in porous media. 

Benzotrifluoride 1 is a colorless, low viscosity liquid. Its polarity is intermediate between those of dichloromethane and ethyl acetate, and it is miscible with common organic solvents and able to dissolve many organic compounds. Benzotrifluoride is used in a wide variety of reactions including radical reactions, oxidations and reductions, phase-transfer reactions, transition metal catalyzed processes and Lewis acid reachons. Ogawa and Curran reported that dichloromethane (CH2CI2) is replaceable by BTF in many instances [8]. 

In the case of a polymer that is miscible in all proportions with its monomer (e.g., styrene and methyl methacrylate), a very large variation of the range of the dispersed-phase viscosity is observed during the course of polymerization. The initially low viscosity liquid monomer is transformed gradually into an increasingly viscous polymer in monomer solution and, as conversion increases, the dispersed phase acquires the characteristics of a solid particle. Rapid polymerization during the sticky stage minimizes the... 

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