Experimental estimation of gas-transport properties of linear low-density polyethylene membranes by an integral permeation method

In recent years, we have investigated gas-transport phenomena in coextruded linear low-density polyethylene (LLDPE) membranes. For the most part, coex truded LLDPE membranes were investigated because of their excellent mechani cal properties, which explain their extensive use in the packaging industry . Because of the small thickness of coextruded LLDPE membranes, significant errors can be involved in the determination of the diffusion coefficient o f gases in the membranes by the time-lag method. To obtain more precise tra nsport parameters for LLDPE membranes, we determined the permeability and d iffusion coefficients for O-2, CO2, He, and N-2 from 298 to 348 K by employ ing an alternative method recently developed. The results indicate that the procedure used in this study for determining the diffusivity of gases in m embranes was precise and more efficient than a method based on the evaluati on of the time-lag parameter. With respect to permeability, the coefficient s obtained in this work agree satisfactorily with those obtained by the tim e-lag method. In general, the permeability and diffusivity results are in s atisfactory agreement with the literature values reported for semicrystalli ne polyethylene membranes. (C) 2001 John Wiley & Sons, Inc.