Ethylbenzene-polystyrene system

Biesenberger and Kessidis were able to correlate their experimental data at atmospheric pressure in terms of N in accordance with Eq. (36) [their Eqs. (4)-(9)], but the diffusion coefficient which they computed using Eq. (36) along with the experimental data was found to be roughly D = 10 m sec" at 177°C. Again, if the ethylbenzene-polystyrene system is used as a basis for comparison, Duda et al. (1982) report a value of 3 x 10"" m /sec at 178°C, which is considerably smaller than the value obtained by Biesenberger and Kessidis (1982). In the experiments con-... 

In a study in which styrene was stripped from polystyrene, Latinen (1962) concluded that his theory correctly described the dependence of mass transfer rates on screw speed and flow rate. This conclusion was based on the agreement obtained between the measured and predicted exit concentration of styrene over a broad range of screw speeds and flow rates (Fig. 8). But, agreement between the theoretical expression and the experimental data was obtained using a diffusion coefficient of the order of 3 X 10 m sec , at 2(X)°C a value which is unrealistically high for this system. If the system ethylbenzene-polystyrene—which has a diffusion... 

Figure 4 A Deborah number diagram for the polystyrene-ethylbenzene system showing the diffusion behavior as a function of weight fraction and temperature. (From Ref. 33.)...

One of the earliest published studies on extraction in twin-screw extruders was conducted by Todd (1974). In this work devolatilization was conducted under vacuum using two different polymeric systems, polystyrene in one and polyethylene in the other. In the case of polystyrene, styrene was not used as the volatUe component so as to avoid problems associated with further polymerization or depolymerization instead, use was made of mixtures of thiophene and toluene or ethylbenzene. Todd found good agreement between the measured exit concentrations of the volatile component and the predicted values using Pe = 40 in the solution to Eq. (38) (see Fig. 15). The value of 5 in Eq. (39) was not reported and it is not known whether a value was chosen to provide a fit with the data or whether it was known a priori. In any event, what is clear is that the exit concentration varies with IVwhich suggests that mass transfer is occur-... 

The reachon of benzene with ethylene or propylene to form ethylbenzene or isopropylbenzene (cumene) is an industrially important transformahon, with ethylbenzene as the key building block for polystyrene and cumene as the feedstock for phenol produchon [55]. Fthylbenzene was originally produced with a Lewis acid catalyst consishng of AlCfi or a Bronsted acidic solid phosphoric acid (SPA) catalyst [56]. Both catalyst systems suffered from equipment corrosion so, in the 1980s the Mobil-Badger vapor phase alkylation process was introduced, which... 

This example uses the Chen et al. method to show how experimental results can be compared graphically to model predictions. The file containing experimental data for the polystyrene-ethylbenzene system must first be created using the POLYDATA program. This file contains all the data for this system in the finite concentration VLE data base. The Tutorial for POLYDATA describes how to create this file. 

The effect of U on the retention of polystyrene in ethylbenzene is typical of most polymer-solvent systems. Therefore, fluctuations in T, of only a couple degrees are generally not a problem. Larger fluctuations can be a significant problem, however, especially when retention is used to monitor small batch-to-batch variations in a quality control situation. The magnitude of U depends on several factors. Heat, which is transferred from the hot wall, is typically removed by heat exchange with water flowing beneath the cold wall. 

As noted above, flow FFF is not limited to aqueous systems. Using a solvent-compatible cellulose nitrate membrane, we have shown that polystyrenes can be fractionated in an ethylbenzene carrier by flow FFF, as shown in Figure 8.16. The universal scope of flow FFF is further confirmed by noting that this subtechnique has been applied to samples as varied as virus particles, silica colloids, polystyrene beads, humic materials, proteins, and protein aggregates. 

Duda for the system of polystyrene and ethylbenzene. This effect in combination with the low monomer concentrations accounts for the fact that secondary reactions of the macroradicals with small molecules capable of diffusion of inert free radicals play a dominant role in the final phase of free radical bulk polymerization. 

Concentration of Monomer in the Reaction Locus.—Blackley and Haynes have published data for the emulsion pol3rmerization of styrene in the presence of organic diluents which are open to the interpretation that the concentration of monomer in the reaction locus in the absence of diluent is not the same as it would have been were no monomer being consumed by polymerization. Whatever is the correct interpretation of these results, they are interesting in themselves as showing just how sensitive the rate of an emulsion polymerization reaction can be to the presence of an apparently inert diluent. Thus the rate of emulsion polymerization of styrene in the presence of, say, ethylbenzene (a good solvent for polystyrene) is approximately third order with respect to the concentration of styrene in the oil phase of the reaction system as a whole. 

Based on the work by Vrentas et al. (1983) for polystyrene-ethylbenzene, where Xip = 0.35, and similar systems, fS u resulting in... 

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