A method to measure diffusion coefficients in plastic films and coatings is described.
This method is based on weighing absorbed amounts of water when conditioned samples are exposed to water or water vapour. A similar procedure based on weight loss is also possible. The same method can be also be applied to measuring diffusion coefficients of organic solvents in plastic films and coatings. The results of this project have confirmed that the use of desiccators should be limited to conditioning samples only, and not for establishing conditions for following the absorption or desorption of water, for example. Experimental results confirm the need to report the information required in the proposed Nordtest method POLY 188 “Measurement of Diffusion Coefficients”.