A modified SAFT equation of state is developed by applying the perturbation theory of Barker and Henderson to a hard-chain reference fluid. With conventional one-fluid mixing rules, the equation of state is applicable to mixtures of small spherical molecules such as gases, nonspherical solvents, and chainlike polymers. The three pure-component parameters required for nonassociating molecules were identified for 78 substances by correlating vapor pressures and liquid volumes. The equation of state gives good fits to these properties and agrees well with caloric properties. When applied to vapor-liquid equilibria of mixtures, the equation of state shows substantial predictive capabilities and good precision for correlating mixtures. Comparisons to the SAFT version of Huang and Radosz reveal a clear improvement of the proposed model. A brief comparison with the Peng-Robinson model is also given for vapor-liquid equilibria of binary systems, confirming the good performance of the suggested equation of state. The applicability of the proposed model to polymer systems was demonstrated for high-pressure liquid-liquid equilibria of a polyethylene mixture. The pure-component parameters of polyethylene were obtained by extrapolating pure-component parameters of the n-alkane series to high molecular weights.

The perturbed-chain SAFT (PC-SAFT) equation of state is applied to pure associating components as well as to vapor-liquid and liquid-liquid equilibria of binary mixtures of associating substances. For these substances, the PC-SAFT equation of state requires five purecomponent parameters, two of which characterize the association. The pure-component parameters were identified for 18 associating substances by correlating vapor pressure and liquid density data. A comparison to an earlier version of SAFT confirms the good results for pure substances. When only one associating compound is present in a mixture, the PC-SAFT equation of state does not require mixing rules for the association term. Using one binary interaction parameter k ij for the dispersion term only, the model was applied to azeotropic and nonazeotropic vapor-liquid equilibria at low and at high pressures, as well as to liquid-liquid equilibria. Simple mixing and combining rules were adopted for mixtures with more than one associating compound, introducing no additional binary interaction parameter. The simultaneous description of liquidliquid and vapor-liquid equilibrium was also possible with a single k ij parameter.

in Wiley InterScience (www.interscience.wiley.com). Accounting for dipolar interactions in a physically based equation of state (EOS) can substantially improve the modeling of phase equilibria of real mixtures. An EOS contribution for dipolar interactions of nonspherical molecules is developed based on a third-order perturbation theory. Molecular simulation data for vapor-liquid equilibria of the two-center Lennard-Jones (2CLJ) plus pointdipole fluid is used to determine model constants of the EOS. The resulting model is compared to simulation data of pure dipolar nonspherical molecules and their mixtures and an excellent agreement is found. The proposed dipole term is applied to real substances with the perturbed-chain statistical associating fluid theory (PC-SAFT) EOS and it is confirmed that accounting for dipolar interactions not only reduces the binary interaction parameter, but also improves the

The perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state is applied to binary and ternary mixtures of polymers, solvents, and gases. The three pure-component parameters required for nonassociating molecules were identified for six polymer compounds. The phase equilibrium of polymer systems, which often involves high-pressure liquid-liquid mixtures as well as vapor-liquid mixtures at lower pressures, was investigated. Using a constant binary interaction parameter (k ij ), the PC-SAFT equation of state gives good correlations of the appropriate phase behavior over wide ranges of conditions. Comparisons to an earlier version of SAFT reveal an improvement of the proposed model.

in Wiley InterScience (www.interscience.wiley.com). An equation-of-state (EOS) contribution for quadrupolar interactions is developed based on a third-order perturbation theory. Model constants are adjusted to comprehensive molecular simulation data for vapor-liquid equilibria of the two-center LennardJones (2CLJ) plus pointquadrupole fluid from the literature. Molecular elongations L* from 0 (spherical) to 0.8 are covered by the simulation data. The EOS is suited for both, the 2CLJ fluid and the tangent-sphere Lennard-Jones framework. It is applied to pure components and mixtures of real substances with the perturbed-chain statistical associating fluid theory (PC-SAFT) EOS. It is possible to use tabulated values of quadrupolar moments (independently determined) directly in the EOS

No abstract

The perturbed-chain SAFT equation of state is extended to heterosegmented molecules and is applied to copolymers with a well-defined (alternating) repeat-unit sequence as well as to systems with a statistical sequence of the monomers in the backbone. Copolymers with a statistical sequence of the constituting repeat units usually require an assumption on the sequence of neighboring repeat units within the chain. A simple approach for defining such repeat-unit arrangements is proposed. Systems containing polyolefine copolymers (poly(ethylene-co-propylene) and poly(ethylene-co-1-butene)) covering the complete range of copolymer composition (including both of the appropriate homopolymers) were modeled in a mixture with solvents. Good results were found for mixtures of copolymer/solvent systems using constant interaction parameters. Copolymers comprising both nonpolar and polar repeat units, for example, poly-(ethylene-co-vinyl acetate) and poly(ethylene-co-methyl acrylate), require an interaction parameter correcting the interactions between repeat units of different types, which depends on the repeat-unit composition.

In this work we propose a new predictive entropy-scaling approach for Newtonian shear viscosities based on group contributions. The approach is based on Rosenfeld's original work [Y. Rosenfeld, Phys. Rev. A 1977, 15, 2545 -2549. The entropy scaling is formulated as third order polynomial in terms of the residual entropy as calculated from a group-contribution perturbed chain polar statistical associating fluid theory (PCP-SAFT) equation of state. In this study we analyze the course of entropy scaling parameters within homologous series and suggest suitable mixing rules for the parameters of functional groups. The viscosity of non-polar, of polar, and of selfassociating (hydrogen bonding) components are considered. In total 22 functional groups are parametrized to viscosity data of 110 pure substances, from 12 different chemical families. The mean absolute relative deviations (MADs) to experimental