Solvent evaporation rates

Design ventilation system to handle the peak solvent evaporation rate... 

In this way, the liquid can be transferred at a speed corresponding to the evaporation speed. The fraction to be analysed is contained in a loop (see Eigure 2.5), connected to a switching valve. By opening the valve, the sample in the loop is driven by the carrier gas into the GC unit (8), instead of the LC pump. An early vapour exit is usually placed after a few metres of the deactivated precolumn (9) and a short piece (3-4 m) of the main column (retaining precolumn). This valve is opened during solvent evaporation in order to reduce the amount of solvent that would reach the detector, and at the same time, to increase the solvent evaporation rate (6). 

The printability of the LEP ink is determined by a number of factors, including the viscosity of the ink, the solvent evaporation rate, and the interactions between the ink and the screen, emulsion, and substrate. Screen-printable solutions normally require considerably... 

For a specific paint application, a mixture of solvents is needed. The mixture is going to be identified by its ability to mix with water (total miscibility), normal boiling point (determines the solvent evaporation rate), the solubility parameter (determines if it is soluble in the paint) and molecular weight (size the candidate molecule). 

Fig. 11. Dependence of the peel strength of tin plate/epoxy systems on coating thickness for coatings cast from DTPM and methyl cello-solve. These theoretical curves were constructed using experimental values for modulus, critical coating thickness, solvent evaporation rate, solution concentration and interfacial work of adhesion96 (Reprinted from Ref. 96, p. 123 by cautesy of Plenum Press)...

A multicomponent gas flow contains a uniform distribution of small droplets of an organic solvent called A. The droplets have a diameter d and a number density Q [m-3]. The solvent evaporation rate m"k (kg/s-m2) depends on the gas-phase concentration of A. It may be assumed that the volume occupied by the droplets is negligible. 

Fig. 6.1 (a) Electron micrograph showing micellar aggregates in a blend of a PS-PMMA diblock (A/w = 175kgmol1, /ps0.53) in a blend with PS homopolynier (A/w = 95 kg mol 1) with a copolymer volume fraction c = 0.3, at room temperature (Lowenhaupt and Hellmann 1991). (b) Enlargement of a micellar aggregate. R denotes the solvent evaporation rate. 

The Italian authors have also studied the effect of the annealing and of the solvent evaporation rate on the morphology and on the mechanical properties of different Kratons114-117. Kraton 1102 exhibits a Mullins effect which increases with annealing. Films with thickness between 0.2 and 0.4 mm, cast from dilute solution (1%) in cyclohexane and methylethyl ketone (MEK) at different rates have been... 

In synthetic laboratories, the most common method to obtain crystals is crystallization from solution. In a way this is also the most difficult process to control. The solvent evaporation rate can be affected by several factors such as ambient humidity, temperature and ventilation, thermal excursion during the 24 h in the case of open air room temperature crystallizations, and vibrations of the building (footsteps, traffic, lifts, etc.) and of the refrigerators. There is no unique and transferable recipe for the crystallization of a substance Philip Ball concluded his Nature Editorial in 1996 by saying, the precipitation of good single crystals remains a black magic [68]. 

CIJ inks need to work on numerous substrates and there is a relationship between drop spread on a substrate and print quality. The amount of drop spread depends upon a number of issues in a CIJ ink, including surface tension, viscosity, solvent evaporation rate, interaction with substrate, amount and type of polymer in the ink etc. You may wish to improve the print quahty of a certain ink-substrate combination by optimally adjusting the drop spread. A common method to do this is by adding a surfactant to the ink formulation. Depending upon the chemistry of the surfactant, it will either increase or decrease drop spread, and hence is a good mechanism for tuning print quality. There are many hundreds of surfactants available, and you can use all chemical types, including anionic, cationic, non-anionic forms. Specific examples include polyoxyethylene fatty ethers and diethylhexyl sodium sulphosuccinate. 

The interaction between the ink and the substrate, both during and after deposition, strongly influences the quality of printing. Dynamic ink-substrate interactions such as ink drop impact, wetting, spreading, penetration, and solvent evaporation rate, as well as drying and coalescence of the ink particles on the substrate, are aU important factors. 

In the modified procedure, the organic solution was distilled under vacuum until the batch concentration exceeded the solubihty limit. In order to avoid undesited spontaneous nucleation, seed was charged at this point and the batch was aged to develop a seed bed. Following the seed age, toluene was fed and THF was distilled continuously under vacuum while maintaining the same batch volume. On completion of the distillation, additional hexane was added to minimize product loss in the mother hquor. The key parameters for this process are construction of the solubility map, determination of the seeding point, and control of the solvent evaporation rate to release the supersatrrration at the proper rate. 

Several years ago, an extended experimental program was carried out by G. M. Sletmoe (Shell Development Co.) geared towards helping the coatings formulator and pressmen to utilize solvent blends effectively. These studies involved determination of solvent evaporation rates for both neat solvent blends and alkyd resin solutions. Sletmoe also determined isotherms showing solvent activity in resin solutions through isopiestic measurements to relate evaporation rates to equilibrium solvent partial pressures. Some of these data have been published (2, 3, 4) with guideline observations and rules for their application. 

It is proposed that rather than feeding a coolant to the reactor, a solv be added that can be easily boiled off, even at moderate temperatu The solvent has a heat of vaporization of 1000 Btu/lb and initially ih are 25 lb mol of A placed in the tank. The initial volume of solvent i reactant is 300 Determine the solvent evaporation rate as a funct of time. What is the rate at the end of 2 h ... 

Evaporation Rate of Solvents. Evaporation rate and solvency are the two most important properties of solvents and provide a good guide for development of useful formulas for various types of coatings. 

Depositing polymer membranes from solution is probably the oldest and simplest method for polymer deposition. Typically a solution of the polymer is deposited onto the transducer surface and allowed to dry. Although this technique is simple to practice, it is a fine art to perfect. Polymer concentration, solvent composition, amount of solution deposited, and solvent evaporation rate are all crucial parameters to control in order to obtain films that adhere well to the substrate, are uniform in thickness, and are free from defects. Gregg and Heller have solution cast redox-functional hydrogels containing glucose oxidase on an electrode to fabricate a glucose sensor [19]. 

Mesoscale crystalline morphology, crystallinity, and molecular orientation in these deposited thin films strongly depend on molecular properties [17,18], chemical nature of the solvent, and processing condition, resulting in very different field-effect mobilities [15,23,36]. Specifically, due to heterogeneous surface-induced (epitaxy) crystal growth as a nature of semicrystalline polymers, fine control of substrate properties and solvent evaporation rate tends to yield favorable molecular orientation of these polymers (i.e., edge-on structure with respect to dielectric substrates) in solution-deposited films [24,66]. 

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