Volume 89, Issue 8 pp. 2201-2209

Phase behavior, density, and crystallization of polyethylene in n-pentane and in n-pentane/CO2 at high pressures

Wei Zhang

Wei Zhang

Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061

Search for more papers by this author
Cigdem Dindar

Cigdem Dindar

Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061

Search for more papers by this author
Zeynep Bayraktar

Zeynep Bayraktar

Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061

Search for more papers by this author
Erdogan Kiran

Corresponding Author

Erdogan Kiran

Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061

Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061===Search for more papers by this author
First published: 11 June 2003
Citations: 18

Abstract

The phase behavior and volumetric properties of polyethylene (PE) in solutions of n-pentane and n-pentane/CO2 were studied in a temperature (T) range of 370–440 K at pressures up to 60 MPa. Measurements were conducted with a variable-volume view-cell system equipped with optical sensors to monitor the changes in the transmitted light intensity as the P or the T of the system was changed. Lower-critical-solution-temperature-type behavior was observed for all of the liquid–liquid (L–L) phase boundaries, which shifted to higher pressures in solutions containing CO2. The solid–fluid (S–F) phase boundaries were investigated over a P range of 8–54 MPa and took place in a narrow T range, from 374 to 378 K in this P interval. The S–F phase boundary showed a unique feature in that the demixing temperatures showed both increasing and decreasing trends with P depending on the P range. This was observed in both the PE/n-pentane and PE/n-pentane/CO2 mixtures. The density of these solutions were measured as a function of P at selected temperatures or as a function of T at selected pressures that corresponded to the paths followed in approaching the phase boundaries (S–F or L–L) starting from a homogeneous one-phase condition. The data showed a smooth variation of the overall mixture density along these paths. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2201–2209, 2003

The full text of this article hosted at iucr.org is unavailable due to technical difficulties.