Critical points of mixtures of ethylene and polyethylene wax under high pressure

Critical points of systems of ethylene with different polyethylene wax mixtures have been measured in the temperature range 413 to 513 K and at pressures up to 93 MPa. The results show a distinct influence of the polydispersity of the polyethylene wax on the critical point. A methodology for evaluating critical points of mixtures of ethylene and polydisperse polyethylene wax with a cubic equation of state and the Wong-Sandler mixing rule is proposed. We find that this method is able to predict critical points with good accuracy over a wide range of polydispersity. For industrial calculations it is advantageous to have a simple model with a limited number of parameters. This method applicates simple cubic equations of state to mixtures under high pressure. (C) 1998 Elsevier Science B.V. All rights reserved.