Weight fraction, 25 Work

The second term in brackets in equation 36 is the separative work produced per unit time, called the separative capacity of the cascade. It is a function only of the rates and concentrations of the separation task being performed, and its value can be calculated quite easily from a value balance about the cascade. The separative capacity, sometimes called the separative power, is a defined mathematical quantity. Its usefulness arises from the fact that it is directly proportional to the total flow in the cascade and, therefore, directly proportional to the amount of equipment required for the cascade, the power requirement of the cascade, and the cost of the cascade. The separative capacity can be calculated using either molar flows and mol fractions or mass flows and weight fractions. The common unit for measuring separative work is the separative work unit (SWU) which is obtained when the flows are measured in kilograms of uranium and the concentrations in weight fractions. 

Ternary-phase equilibrium data can be tabulated as in Table 15-1 and then worked into an electronic spreadsheet as in Table 15-2 to be presented as a right-triangular diagram as shown in Fig. 15-7. The weight-fraction solute is on the horizontal axis and the weight-fraciion extraciion-solvent is on the veriical axis. The tie-lines connect the points that are in equilibrium. For low-solute concentrations the horizontal scale can be expanded. The water-acetic acid-methylisobutylketone ternary is a Type I system where only one of the binary pairs, water-MIBK, is immiscible. In a Type II system two of the binary pairs are immiscible, i.e. the solute is not totally miscible in one of the liquids. 

In this early work, both initiation and termination were seen to lead to formation of structural units different from those that make up the bulk of the chain. However, the quantity of these groups, when expressed as a weight fraction of the total material, appeared insignificant. In a polymer of molecular weight 100,000 they represent only ca 0.2% of units Thus, polymers formed by radical polymerization came to be represented by, and their physical properties and chemistry interpreted in terms of, the simple formula 1. 

For semibatch operation, the term fraction conversion is somewhat ambiguous for many of the cases of interest. If reactant is present initially in the reactor and is added or removed in feed and effluent streams, the question arises as to the proper basis for the definition of /. In such cases it is best to work either in terms of the weight fraction of a particular component present in the fluid of interest or in terms of concentrations when constant density systems are under consideration. In terms of the symbols shown in Figure 8.20 the fundamental material balance relation becomes ... 

Chen et al. [92] also performed self-nucleation experiments by DSC in PB-fr-PEO diblock copolymers and PB/PB-b-PEO blends. The cooling scans presented in their work showed that a classical self-nucleation behavior was obtained for PEO homopolymer and for the PB/PB-b-PEO blend where the weight fraction of PEO was 0.64 and the morphology was lamellar in the melt. For PB/PB-fr-PEO blends with cylinder or sphere morphology, the crystallization temperature remained nearly constant for several self-seeding temperatures evaluated. This observation indicates that domain II or the self-nucleation domain was not observable for these systems, as expected in view of the general trend outlined earlier. 

The partial blocking of the GPC column with 5 x 10 A exclusion limit in both dichloromethane and H.-methylpyrrolidone may be attributed to the presence of hemicellulose in both unfractionated triacetate samples and high molecular weight fractions used in this work. The blocking of the column in question was Indicated... 

First, work together to create a table of weight fractions in increments of 0.1 from 0.1 to 0.9 for example, Xb =0.1, 0.2, and so on, and their corresponding volume fractions using the equation above. Then perform the following calculations separately. 

The line widths of C-l—C-S 13C resonance peaks in the gel are about 150 Hz, which are rather broad in comparison with those of alkaline solution (0.22M NaOH)(Fig. 2D) and also with those of the lower molecular weight fraction (Fig. 3A). By comparing the integrated peak intensities (with nuclear Overhauser effect sur-pressed) with those of the corresponding peaks in the 0.22M NaOH solution, in which the curdlan molecules are considered to have random-coil conformation, it was estimated that these observed 13C peaks account for only 20-30 and 60% for the C-1--C-5 and C-6 carbons of the total gel, respectively. Hence, the remaining invisible portion of the 13C should be ascribed to the junction zones of the gel net work and to residues located closely to these junctions. 

In most cases it is necessary to work backward from the weight fractions vc, ... 

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