Moisture absorption and diffusion characterisation of packaging materials - advanced treatment

Unlike thermo-mechanical properties, moisture properties of packaging materials are rarely reported, even though moisture has been known to be at least as damaging as temperature to plastic packaging. This is in part due to the lack of characterisation knowledge for such properties. This paper tries to address this issue through a comprehensive presentation of the characterisation techniques for moisture sorption and diffusion properties. Special focuses are given to advanced treatments on unique characteristics of polymeric packaging materials. The effect of aspect ratio of the test specimen on characterisation accuracy has been analysed and correction factor has been formulated. Two techniques for characterising anisotropic diffusivity are presented and illustrated with actual experimental data on organic laminates. The techniques and challenges of characterising moisture diffusivity at high temperature are presented. A new insight into the causes and physics of non-Fickian adsorption in polymeric packaging materials is presented along with a technique to alleviate the associated characterisation challenge. (C) 2003 Elsevier Ltd. All rights reserved.