Ethylene and 1-hexene sorption in LLDPE under typical gas-phase reactor conditions: Experiments

The sorption of ethylene and 1-hexene and their mixture in three poly(ethylene-co-1-hexene) samples is measured gravimetrically at temperatures 70, 90, and 150 degrees C and pressures 0-30 bar. Gravimetric sorption measurements are supplemented with microscopic observations of swelling of polyethylene particles caused by sorption and the extent of swelling is found to be significant. Experimental data are compared with predictions of PC-SAFT (perturbed chain-statistical associating fluid theory) equation of state. Comparison of sorption data in semicrystalline polymer (measured at 70 and 90 degrees C) and amorphous polymer (at 150 degrees C) demonstrates the constraining effect of semicrystalline structure. Solubilities of penetrants in investigated samples are not observed to depend on the content of 1-hexene in copolymers. The solubility of the mixture of ethylene and 1-hexene is smaller than the sum of solubilities of individual components at 70 and 90 degrees C. (c) 2006 Wiley Periodicals, Inc.