Propylene critical point

In Fig. 10.3-2 we have plotted, for various fixed compositions, the bubble and dew point pressures of this mixture as a function of temperature. The leftmost curve in this figure is the vapor pressure of pure ethane as a function of temperature, terminating in the critical point of ethane (for a pure component, the coexisting vapor and liquid are necessarily of the same composition, so the bubble and dew pressures are identical and equal to the vapor pressure). Similarly, the rightmost curve is the vapor pressure of pure propylene, terminating at the propylene critical point. The intermediate curves (loops) are the bubble and dew point curves relating temperature and pressure for various fixed compositions. Finally, there is aline in Fig. 10.3-2 connecting the critical points of the mixtures of various compositions this line is the critical locus of ethane-propylene mixtures. 

On the basis of this approach, a triblock copolymer of ethylene oxide (EO) and propylene oxide (PO), HO(EO) (PO)m(EO) OH was analyzed with respect to the PPO inner block and the PEO outer blocks by LCCC and SEC (Adrian et al., 1998). For the selective separation of the block copolymer with respect to the PPO block, experiments were conducted using chromatographic conditions, corresponding to the critical point of PEO. These could be established on a RP-18 stationary phase when an eluent of methanol-water 86 14 (v/v) is used. The separation of the triblock copolymer at the critical point of PEO is shown in Fig. 17.15. 

The critical locus in Figure I0.3-3n is very much like that for the ethane-propylene system in Fig. 10.3-2 this is referred to as category I phase behavior. For such systems the critical line starts at the critical point of pure component 1 (C ), and as the mixture... 

Fig. Phase diagram of the mixture polystyrene and polyvinyl methyl ether, molecular weights being = 62700 (PVME) and Mw = 60(W0 (PS), as obtained from light scattering. The lower curve describes the miscibility gap binodaF, coexistence curve ), the upper curve describes the spinodal curve, which touches the coexistence curve in the critical point. The shaded region in between binodal and spinodal is believed to describe homogeneously mixed metastable one-phase states. From Snyder et al. [27]. b Phase diagram for polyisoprene-poly(ethylene-propylene) with molecular weights of 2000 and 5000, respectively. From Cumming et al [70]...

For the hydroformylation of propylene in SCCO2, the critical point data (Tc and Pc) of various mixtures of the related components (CO2, H2, CO, propylene, n- and wo-butyraldehyde) have been measured. These data will be very useful for designing reaction conditions in SCCO2 - for example, for avoiding phase separation during the reaction. 

The separation of triblock copolymers of ethylene oxide (EO) and propylene oxide (PO), namely HO(EO) (PO), (EO) OH, at the critical point of the EO outer blocks is shown in Fig. 19 [16]. At this point the EO blocks were... 

Coefficients of the equadon of state and of the equation for transport properties are stored for each substance. Parameters of the critical point and coefficients of equations for calculadon of the ideal-gas functions, the saturated vapor pressure and the melting pressure are kept also. The thermal properties in the single-phase region and on the phase-equilibrium lines can be calculated on the basis of well-known relations with use of these coefficients. The system contains data for 30 reference substances monatomic and diatomic gases, air, water and steam, carbon dioxide, ammonia, paraffin hydrocarbons (up to octane), ethylene (ethene), propylene (propene), benzene and toluene. The system can calculate the thermophysical properties of poorly investigated gases and liquids and of multicomponent mixtures also on the basis of data for reference substances. 

Macromolecular Materials and Engineering 286, No.3, 30th March 2001, p.161-7 MATRIX-ASSISTED LASER DESORPTION/ IONIZATION MASS SPECTROMETRY OF SYNTHETIC POLYMERS, 5A. ANALYSIS OF POLY(PROPYLENE OXIDE)S BY COUPLED LIQUID CHROMATOGRAPHY AT THE CRITICAL POINT OF ADSORPTION AND MALDI-TOF MASS SPECTROMETRY Keil C Esser E Pasch H Darmstadt,Deutsches Kunststoff-Institut... 

Though offering good olefin/paraffin separation performances at laboratory scale, those materials were subject to a loss of solvent by evaporation, which resulted in dramatic fall of olefin/paraffin separation performances. In order to maintain the separation performances of those membranes, the feed had thus to be saturated with vapor in order to prevent the drying of the membrane. This is a critical point as, at industrial scale, propylene/propane mixtures are dehydrated before being fractionated by distillation. 

A first systematic study of such system was performed on the relatively large-molar-mass symmetric polyolefins PE and PEP and the corresponding diblock copolymer PE-PEP PE being polyethylene and PEP being poly(ethylene propylene). A mean-field Lifshitz like behavior was observed near the predicted isotropic Lifshitz critical point with the critical exponents y=l and v=0.25 of the susceptibility and correlation length, and the stmcture factor following the characteristic mean-field Lifshitz behavior according to S(Q)ocQ". Thermal composition fluctuations were apparently not so relevant as indicated by the observation of mean-field critical exponents. On the other hand, no Lifshitz critical point was observed and instead a one-phase channel of a polymeric bicontinuous miaoemulsion phase appeared. Equivalent one-phase channels were also observed in other systems. 

An application has been found in which a system that exhibits an upper, or lower, critical consolute point, UCST or LCST, respectively, is utilized. At a temperature above or below this point, the system is one homogeneous liquid phase and below or above it, at suitable compositions, it splits into two immiscible liquids, between which a solute may distribute. Such a system is, for instance, the propylene carbonate - water one at 25°C the aqueous phase contains a mole fraction of 0.036 propylene carbonate and the organic phase a mole fraction of 0.34 of water. The UCST of the system is 73 °C (Murata, Yokoyama and Ikeda 1972), and above this temperature the system coalesces into a single liquid. Temperature cycling can be used in order to affect the distribution of the solutes e.g. alkaline earth metal salts or transition metal chelates with 2-thenoyl trifluoroacetone (Murata, Yokayama and Ikeda 1972). 

Literature values of the critical surface tension of skin range from 26 to 27.5 dynes/cm (2, 11, 12). In all these cases, aqueous solutions of materials such as acetone 2,13) or propylene glycol (11) were used for the 7c determination to obtain an appropriate range of liquid surface tensions. Dann (9), however, has pointed out that jc values obtained in this way will be less than the value obtained with liquids, such as hydrocarbons, which do not possess a component. Correcting an experimental value of 27.5 dynes/cm for this eflFect, Rosenberg et at. (12) obtained 37.0 dynes/cm for jc. As suggested by Murphy et al. (13) in their work on wetting by aqueous alcohol solutions, the above eflFects are probably linked to preferential adsorption of the solute onto the solid. 

Figure 10.3-2 The bubble point, dew point, and critical locus for the ethane-propylene system.

Smoke point of a turbulent flame is defined as the critical fuel mass flow rate (CFMFR) beyond which the flame does not smoke. Goh [88] studied the effects of nitrogen dilution on the smoke point characteristics of propylene diffusion flames in crossflow. Figure 29.20 shows the variation of diluent mass flow rate with fuel... 

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