PC-SAFT thermodynamics of EVA copolymer - Solvent systems

- A rigorous thermodynamic assessment to model the separation stage of EVA solution production process, with methanol (MET) as solvent.
- The analysis includes determining the binary parameters between the components involved in the process, with the best association scheme.
- A simulation of the separation column was carried out, with mass flow average deviations lower than 1%.

This work presents a rigorous thermodynamic assessment aimed to model the separation stage of the Ethylene Vinyl Acetate copolymer (EVA) dissolution production process, with methanol (MeOH) as solvent. The employed thermodynamic model was the PC-SAFT equation of state, whose application involves splitting the EVA copolymer in its homopolymers, polyethylene (PE) and polyvinylacetate (PVA).The thermodynamic analysis includes the determination of the binary parameters (kij) to account for all the possible binary interactions among the components participating in the process (PE, PVA, MeOH and VAM). The best association scheme to describe the interactions among these compounds was also defined, while the PC-SAFT parameters of the pure components were taken from bibliography.The homopolymers/solvents binary parameters were calculated by adjusting the solvent sorption curves previously reported in literature. The solvent/solvent interaction parameters were obtained from the V-L equilibrium data previously reported for MeOH/VAM system. Finally, the homopolymer/homopolymer binary parameter was determined from the sorption curves of the EVA copolymer and its homopolymers in cyclohexane (CH).Finally, once all the PC-SAFT interaction parameters were known, a simulation of a distillation column involved in the separation step was carried out, obtaining an average deviation between predicted and literature values, for the mass flow of each compound, lower than 1%.

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