Modeling Copolymer Systems Using the Perturbed-Chain SAFT Equation of State

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.

Group contribution methodology based on the statistical associating fluid theory for heteronuclear molecules formed from Mie segments

“…56,57 Within the context of a SAFT treatment, several variants have been reformulated based on a heteronuclear tangent molecular model. Examples include the work of Banaszak et al, 58, 59 Adidharma and Radosz, 60,61 McCabe et al 62 and Peng et al 63 who implement a square-well (SW) potential to describe the group-group interactions, the work of Blas and Vega 64 based on molecules formed from Lennard-Jones (LJ) segments, and the work of Gross et al 65 As well as describing molecules with heteronuclear models, it is apparent that a model with fused (as opposed to tangent) segments is needed to provide accurate thermodynamic properties of real fluids. 66,67 Fused models are treated within the SAFT-γ GC approach by representing the heteronuclear molecules as fused SW segments of different type with a shape factor to characterize the degree of overlap between the different groups.…”

Modeling imidazolium-based ionic liquids with ePC-SAFT

“…This is specially required for CO 2 as the CO 2 solubility in ILs can vary from very low to more than 80% in mole fraction. The Perturbed-Chain SAFT (PC-SAFT) model has been proposed [18] and widely used for systems containing non-polar as well as associating and polar substances including gases, solvents, biomolecules, and polymers [19][20][21][22][23][24][25][26]. The polar term has been included to consider the multi-polar interactions [27][28][29].…”

Density gradient theory combined with the PC-SAFT equation of state used for modeling the surface tension of associating systems

“…Significantly better prediction of thermophysical properties and phase equilibria can be achieved for these systems compared to classical cubic EoSs over wide temperature, pressure, and composition ranges. The PC-SAFT EoS can also be used for modeling more complicated systems such as polymers [6], polar substances [7,8], or associating fluids, e.g., mixtures with alkanols [9], or hydrogen sulfide [10].…”