The significance of the zero-concentration diffusivity value obtained fromintegral desorption data

n-Hexane zero-concentration diffusivity in high density polyethylene obtain ed 'indirectly' from integral desorption measurements using the free volume concept was compared with the zero-concentration diffusivity obtained dire ctly at low-n-hexane activities using a quartz-ring system. The difference between the results obtained by the indirect and direct methods was within the experimental error. The concentration dependence of the diffusivity pre dicted by the Cohen-Turnll-Fujita free volume theory was in accordance with experimental data. (C) 2001 Elsevier Science Ltd. All rights reserved.