Examining the adsorption (vapor-liquid equilibria) of short-chain hydrocarbons in low-density polyethylene with the SAFT-VR approach

The versatility of the SAFT-VR approach in the prediction of fluid-phase eq uilibria of complex fluids is illustrated for systems of short and long hyd rocarbons. In particular, we examine the vapor-liquid equilibrium of a mixt ure of methane + hexatriacontane (C36H74) and the adsorption and coadsorpti on of light alkanes on low-density polyethylene. The molecules are modeled as chains of square-well segments, and the approach incorporates separate c ontributions to take into account the effect of monomer-monomer interaction s and the bonding of the segments to form chains. In previous work (McCabe, C.; Jackson, G. Phys. Chem. Chem. Phys. 1999,1, 2057), the phase behavior of pure long-chain n-alkane molecules was examined using the SAFT-VR approa ch; the intermolecular potential parameters were found to tend to a limitin g value as the chain length of the n-alkane increases. Linear relationships with molecular weight for these parameters are used to model the polyethyl ene polymer in this work.