Thermodynamic behavior of ethylene-styrene interpolymers

The Dow Chemical Company has recently introduced a new family of copolymers of ethylene and styrene identified as ethylene-styrene interpolymers (ESIs ). The ability of the group-contribution lattice-fluid equation of state (G CLF EoS) to predict the volumetric properties of a series of ESIs of differ ent compositions, the solubility parameter of a given copolymer, and the so lubility of toluene was tested. The two latter experiments were conducted i n the temperature range 50-150 degreesC. On average, the error in density w as less than 1.1% in the temperature and pressure ranges of 100-250 degrees C and 6.9-690 bar, respectively. The solubility parameter of the polymer wa s measured using inverse gas chromatography. The solubility parameter was f ound to have a strong temperature dependency that the model could not repro duce accurately. At 25 degreesC, however, the model predictions were found to be in the range of the literature data. The GOLF EoS gave good predictio ns for the solubilities of the vapor's at low styrene contents. Discrepanci es at high styrene contents were attributed to a less accurate description of the sorption of solvents in pure polystyrene. The investigation shows th at crystallinity has an influence on the solvent solubilities even if they are treated on a crystal-free basis.