Application of SAFT to Polymers

Abstract

One of the most important first applications of SAFT was the description of phase equilibria of polymer mixtures and thus many of the applications of the original SAFT (or CK-SAFT) 1 included high-pressure phase equilibria for polyethylene and other polyolefins. Of the newest SAFT variants, PC-SAFT especially has been extensively applied to polymers, while applications of SAFT-VR and soft-SAFT to polymers have been reported as well. A variety of polymers and co-polymers have been considered, as well as different types of phase equilibria (VLE, LLE, SLLE, gas solubilities, etc.) and conditions (low and high pressures). Table 14.1 summarizes several applications of SAFT variants and Sections 14.3 and 14.4 will illustrate some applications, especially of simplified PC-SAFT. In Section 14.2 we will address an important issue when extending SAFT models (and other equations of state (EoS)) to polymers, i.e. how the parameters of polymers are obtained. Computational aspects are discussed in Appendix 14.B. Estimation of polymer parameters for SAFT-type EoS Estimation of polymer parameters for EoS: generalObtaining reliable SAFT parameters for polymers (and for other EoS as well) is a difficult task and currently an active research area. This is because methods employed for low-molecular-weight compounds cannot be used since critical properties and vapor pressure data are not available (or have no meaning) for polymers. Thus, indirect methods are needed and various approaches have been tested: