Core/Shell Nanoparticles: Classes, Properties, Synthesis Mechanisms, Characterization, and Applications

Classification, processing and application of hydrogels: A review.

The use of supercritical carbon dioxide as a processing solvent for the physical processing of polymeric materials is reviewed. Fundamental properties of CO2/polymer systems are discussed with an emphasis on available data and measurement techniques, the development of theory or models for a particular property, and an evaluation of the current state of understanding for that property. Applications such as impregnation, particle formation, foaming, blending, and injection molding are described in detail including practical operating information for selected topics. The review concludes with some forward-looking discussion on the future of CO2 in polymer processing.

A Review of CO2 Applications in the Processing of Polymers

In a preceding project, functional forms for “short” Helmholtz energy equations of state for typical nonpolar and weakly polar fluids and for typical polar fluids were developed using simultaneous optimization. In this work, the coefficients of these short forms for the equations of state have been fitted for the fluids acetone, carbon monoxide, carbonyl sulfide, decane, hydrogen sulfide, 2-methylbutane (isopentane), 2,2-dimethylpropane (neopentane), 2-methylpentane (isohexane), krypton, nitrous oxide, nonane, sulfur dioxide, toluene, xenon, hexafluoroethane (R-116), 1,1-dichloro-1-fluoroethane (R-141b), 1-chloro-1,1-difluoroethane (R-142b), octafluoropropane (R-218), 1,1,1,3,3-pentafluoropropane (R-245fa), and fluoromethane (R-41). The 12 coefficients of the equations of state were fitted to substance specific data sets. The results show that simultaneously optimized functional forms can be applied to other fluids out of the same class of fluids for which they were optimized without significant loss of a...

Short Fundamental Equations of State for 20 Industrial Fluids

Structure, dynamics and transport properties of microemulsions

The temperature and acentric factor dependence of the attractive term of the Peng—Robinson equation of state have been modified. The introduction of a single pure compound parameter allows the accurate reproduction of the vapor pressure data for a wide variety of substances. Nonpolar, polar nonassociating and associating compounds are equally well represented by the cubic PRSV equation of state. The conventional one-binary-parameter mixing rule allows the correlation of the vapor—liquid equilibrium data for a wide variety of binary systems. Only for systems formed by a polar compound (associating or not) and a saturated hydrocarbon, are results poorer than those obtained with conventional excess Gibbs energy functions.

PRSV: An improved peng—Robinson equation of state for pure compounds and mixtures

A modified fluid-lattice theory of fluids considering a finite quasi-lattice coordination number and a constant lattice site volume for all r-mers is developed. The theory is tested against experimental information on specific volumes, vapor pressures, orthobaric densities and heats of vaporization of pure components. Some common polymers and some typical polymer solvents have been chosen for testing the theory. The theoretical treatment has been extended to mixtures and tested against experimental data on volumes of mixing, heats of mixing, and χ interaction parameters of polymer solutions. Results have been compared with those obtained with a two-parameter new Flory theory and with the three-parameter new Huggins theory. Both for pure components and for mixtures, the effect of introducing a non-random quasi-chemical correction is discussed.

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Statistical Thermodynamics of r -Mer Fluids and Their Mixtures

Two new composition dependent mixing rules for cubic equations of state are proposed. Both mixing rules contain two adjustable binary parameters and reduce to the conventional one parameter mixing rule when the parameters are equal. Vapor-liquid equilibrium data for mixtures of polar (associated or not) compounds with saturated hydrocarbons and for systems water/alcohol have been used to test the new mixing rules applied to the PRSV cubic equation of state. For these highly nonideal systems, correlation of the data with a new mixing rule of the Van Laar type for the PRSV equation gives better results than those obtained using excess Gibbs energy functions like the Wilson equation, NRTL and UNIQUAC.

“PRSV — An improved peng‐robinson equation of state with new mixing rules for strongly nonideal mixtures”

Sodium-di-(n-octyl) phosphinate (NaL) was used as a precipitating agent to remove heavy metals from aqueous nitrate solutions. Cadmium, zinc and mixtures of lead, cadmium and zinc were precipitated in the form of PbL 2(s) , CdL 2(s) , and ZnL 2(s) . Lowering the pH of the feed solution reduced the removal of the metals as some of the phosphinate precipitated in the acid form as HL (s) . The removal of lead, cadmium, and zinc, from a solution containing the three metals gave a selectivity in the order Zn>Pb>Cd. Predictions of an equilibrium-constant model, using measured solubility products of the precipitates and literature values of stability constants, gave metal removals, loss of precipitating agent, and equilibrium pH in good agreement with measured values.

Juan H. Vera

Papers

PRSV: An improved peng—Robinson equation of state for pure compounds and mixtures

Statistical Thermodynamics of r -Mer Fluids and Their Mixtures

“PRSV — An improved peng‐robinson equation of state with new mixing rules for strongly nonideal mixtures”

Removal of lead, cadmium and zinc from aqueous solutions by precipitation with sodium Di-(n-octyl) phosphinate

PRSV2: A cubic equation of state for accurate vapor—liquid equilibria calculations