Physical and transport properties

7 Physical properties and phase equilibrium calculations 5.7.1 Physical and transport properties 

One of the most important issues in modeling the suspension polymerization process is the evaluation of the physical and transport properties of the reacting system as well as the calculation of composition and partitioning of the different species (e.g., monomer(s), polymer, initiator(s), etc.) in the various phases present in the system. In a suspension polymerization process, one can identify, at least, three phases the dispersed phase (e.g., polymerizing monomer droplets), the continuous aqueous phase and the gas phase. The dispersed phase can be either homogeneous (if the polymer is soluble in its monomer) or heterogeneous (if the polymer is insoluble in its monomer). In the powder suspension polymerization, the dispersed phase consists of two different phases the polymer-rich and the monomer-rich phase. The continuous aqueous phase contains only small amoimts of monomer and, finally, the gas phase contains monomer and water vapors. 

The density of the suspension system, ps, can be calculated by the weighted sum of the densities of the dispersed (pa) and continuous (p ) phases [80]  

Accordingly, the viscosity of the dispersion system can be calculated by the following semi-empirical equation [81]  

For the suspension polymerization of VCM, the viscosity of the polymerizing monomer droplets, can be calculated from the Filers equation [82]  

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Baxter, L.L., T Gale, S. Sinquefield, and G. Sclippa, 1997a. Influence of Ash Deposit Chemistry and Structure on Deposit Physical and Transport Properties. Developments in Thermochemical Biomass Conversion, A.V. Bridgwater and D.G.B. Boocock, eds., Blackie. Academic and Professional Press, London, pp. 1247-1262. 

It is also important to maintain the same gas and liquid used in the bench scale BSCR, the same physical and transport properties, pressure, temperature, and the concentration of reagents in the gas and liquid phases. 

Methods for estimating physical and transport properties are described in Sections 4 and 5 of this handbook [see also Poling et al., The Properties of Gases and Liquids, McGraw-Hill, 5th ed. (2001)]. 

Supercritical fluids possess characteristics that make them interesting for use as polymerization media. A supercritical fluid exists at temperatures and pressures above its critical values. In the supercritical state, the fluid exhibits physical and transport properties intermediate between the gaseous and liquid state. This is illustrated in Table 2. SCFs have liquid-like densities, but gas-like diffusivities. These intermediate properties can provide advantages over liquid-based processes. In particular, the higher diffusivities of SCFs reduce mass transfer limitations in diffusion-controlled processes. Additionally, lower energy is required for processing the supercritical fluid because its viscosity is lower than that of most liquids, and because the need to vaporize large quantities of liquid is avoided. 

The solution scheme is as follows. First, we solve Eq. 10.52 for pressure. With pressure determined, we can calculate fluxes. Then we solve Eq. 10.51 for the total concentrations of N components. With this information known, we can use the reaction equilibrium equations as described in the previous section to calculate all the concentrations. When we know the concentrations, we can determine the phase concentrations, phase saturations, and other physical and transport properties required to solve for pressure for the next time level. 

Various physical and transport properties of these cation-exchange membranes are largely influenced by the amount of elec-... 

B. K. Rubin, O. E. Ramirez, and A. L. Baharav. The physical and transport properties of CF sputum after treatment with rhDNase. Pediatr. Pulmonol. (Suppl 9) 251 (1993). 

Table 5.2 Expressions for membrane physical and transport properties [39]. 

Growing demand spurred innovations to increase production rates and reduce unit costs. As the industry shifted from an empirical basis to one grounded in science, understanding the physical and transport properties of the feedstock and products became more important. As this became apparent, some industry participants created physical property laboratories to determine these properties. 

Theoretical approaches to molecular structure design require accurate estimates of physical and transport properties. These are derived commonly iiom the principles of thermodynamics and transport phenomena, and using molecular simulations. Since the literature abounds with estimation methods, reference books and handbooks are particularly useful sources. One of the most widely used. Properties of Gases and Liquids (Poling et al., 2001), provides an excellent collection of estimation methods and data for chemical mixtures in the vapor and liquid phases. For polymers. Properties of Polymers (van Krevelen, 1990) provides a collection of group-contribution methods and data for a host of polymer properties. 

The foim involving partial pressures is only used for gases, while those involving mass concentrations or mass fractions are usually employed for liquids. When defined in this way the mass transfer coefficient includes effects of geometry, hydrodynamics, physical and transport properties of the fluid, and bulk flow contributions. 

Here we are concerned with single crystals large enough for physical and transport properties characterization or neutron scattering experiments. 

Water Uptake. The physical and transport properties of perfluorinated polymeric cation-exchange membranes are greatly influenced by the amount of water and electrolyte uptake, which depends on the polymer EW, the nature of the electrolyte, and the pretreatment procedures. The water uptake increases [41] with increasing temperature, as shown in Fig. 4.8.3. 

PROPERTY DATA. References [5] and [6] were used as the sources of physical- and transport-property data. Since an insufficient range of property data for hydrogen is available currently, the authors had to igxtrapolate these data in many instances. This was particularly true with respect to viscosity data, which are available for 1 atm only. 

Using a base-case ratio often reduces the need for knowing actual values of physical and transport properties (physical properties refer to thermodynamic and transport properties of fluids), equipment, and equipment characteristics. The values identified in the ratios fall into three major groups. They are defined below and applied in Example 17.2. 

In this chapter, several important tools were introduced that are essential in analyzing equipment performance problems. Base-case ratios are the most important tool. They permit comparison of two cases, usually without complex calculations, and often without the need to know physical and transport properties. Under the circumstances for which it is valid, using a limiting resistance simplifies the base-case ratio. Finally, graphical representation of equipment performance is a useful tool in understanding the physical situation. All these techniques require a minimum of calculations. However, they do provide an intuitive understanding of equipment performance that is very rarely achieved from merely doing repetitive, complex computations. 

Physical and transport properties of bis(trifl.uoromethylsulfonyl)imide-based room-temperature ionic liquids Application to the diffusion of tris(2,2 -bipyridyl)ruthenium(II). Journal of the Electrochemical Society, 158,1, (2010), F1-F9 Papoular, R. J. Allouchi, H. Chagnes, A. Dzyabchenko, A. Carre, B. Lemordant, D. V. Agafonov (2005). X-ray powder diffraction structure determination of y butyrolactone at 180 K phase-problem solution from the lattice energy minimization with two independent molecules. Acta Crystallographica, Section B. Structural Science, B61, (2005), 312-320... 

Pan Y, Boyd LE, Kruplak JF, Cleland WE Jr, Wilkes JS, Hussey C (2011) Physical and transport properties of Bis(trifluoromethylsulfonyl)imide-based room-temperature inic... 

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