Materials Research Institute, Sheffield Hallam University, Pond St. Sheffield , S1 1WB, UK

FTIR-ATR has been used to perform in-situ measurements of water diffusing into poly (ethylene terephthalate) (PET). This work will be used as a point of reference for evaluating the barrier properties of PET-clay nanocomposites at a later stage of this project. The diffusion data is obtained by integration of the n (OH) band. The diffusion coefficient for each run is calculated by fitting the data to a single Fickian model using Mathematica. It is intended to synthesise various PET-clay nanocomposites and to perform similar experiments on these nanocomposites. This data will then be used to correlate the observed barrier properties with the properties of the nanocomposites. Emphasis will be placed on the investigation of the effects clay loading and clay distribution have on the barrier properties of these films.