Thin liquid layers

Side-chain photochlorination of toluene isocyanates yields important industrial intermediates for polyurethane synthesis, one of the most important classes of polymers [6]. The motivation for micro-channel processing stems mainly from enhancing the performance of the photo process. Illuminated thin liquid layers should have much higher photon efficiency (quantum yield) than given for conventional processing. In turn, this may lead to the use of low-intensity light sources and considerably decrease the energy consumption for a photolytic process [6] (see also [21]). 

Low-intensity light sources should give efficient irradiation of thin liquid layers [21]. Sample heating is reduced and so is radical recombination. In addition, oxygen enrichment of solutions before and after micro reactor passage can be handled differently and is no longer a major safety problem [21]. 

Natural convection depends strongly on cell geometry. No convection can arise in capillaries or in the thin liquid layers found in narrow gaps between electrodes. The rates of natural convective flows and the associated diffusion-layer thicknesses depend on numerous factors and cannot be calculated in a general form. Very rough estimates show that the diffusion-layer thickness under a variety of conditions may be between 100 and 500 pm. 

The liquid-liquid interface is not only a boundary plane dividing two immiscible liquid phases, but also a nanoscaled, very thin liquid layer where properties such as cohesive energy, density, electrical potential, dielectric constant, and viscosity are drastically changed along with the axis from one phase to another. The interfacial region was anticipated to cause various specific chemical phenomena not found in bulk liquid phases. The chemical reactions at liquid-liquid interfaces have traditionally been less understood than those at liquid-solid or gas-liquid interfaces, much less than the bulk phases. These circumstances were mainly due to the lack of experimental methods which could measure the amount of adsorbed chemical species and the rate of chemical reaction at the interface [1,2]. Several experimental methods have recently been invented in the field of solvent extraction [3], which have made a significant breakthrough in the study of interfacial reactions. 

Figure 1.7 (a) In the hquid phase, molecules of both compounds are dispersed and all molecules are potentially reactive (b) when two sohds react, reaction can only occur at the point where the two crystallites are in direct contact (c) reaction between solids may form a thin liquid layer which increases the rate of reaction... 

Latex Shelf Life. The shelf life of seed I was greater than 6 months, but none of the latexes produced in the tubular reactor had a shelf life of more than a week. Initially, a thin liquid layer formed at the top. After several weeks, a solid layer formed in the bottom of the container. Despite the high levels of emulsifier used, the large polyvinyl acetate particles separated quickly. No studies were made to increase the shelf life. 

Thin liquid layer with a dissolved mediator Separates a donor solution from an acceptor solution Kinds ... 

Adhesion and cohesion forces in the immobile liquid films between individual primary powder particles. These forces may not contribute significantly to the final granule strength once the granules have been dried. These forces arise from the thin liquid layers around particles that may be generated due to moisture uptake by the powders. This immobile liquid film tends to decrease the inter-particle distances leading to an increase in the van der Waals forces between particles. 

Another annular-flow concept was provided by the so-called dual-channel reactor with two parallel microchannels separated by a wall. In this way, four thin liquid layers in annular flow were created at once (see Figure 4.34, bottom) [274]. In front of this section, the liquid feed enters through a hole directed to the wall, whereas the two gas feeds point to the two reaction channels. Consequently, the liquid flow splits and a larger interface is created than given for single-channel guidance. 

Side-chain photochlorination of toluene isocyanates leads to important industrial intermediates for polyurethane synthesis, one of the most important classes of polymers [264]. Irradiated thin liquid layers in microchannels should have much higher photon efficiency (quantum yield) than given for conventional processing. 

Hartley, D.E. Murgatroyd, W. Criteria for the break-up of thin liquid layers flowing isother-mally over solid surfaces. Int. J. Heat Mass Transfer 1964, 7, 1003-1015. 

Peschel, G. Adlfmger, K. H. (1971). Thermodynamic investigation of thin liquid layers between solid surfaces, n. Water between entirely hydroxylated fused silica surfaces. Z Naturforsch. 26a, 707-715. 

The problems that we consider in this section are closely related to those in the previous section. As shown in Fig. 6-1, we again consider a thin liquid layer that is bounded below by a solid wall, but with an upper surface that is an interface with an upper fluid that we... 

The SECM has been used to form thin liquid layers and probe electrochemical reactions in them. When the tip is pushed through the interface between... 

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