Modelling and Prediction of Barrier Properties of Polymer Layered Silicate Nanocomposites

Different permeation models have been compared with the experimental barrier performance of the polyethylene and polypropylene layered-silicate nanocomposites. It was observed that the models assuming the perfect orientation of filler platelets did not represent the nanocomposite system accurately, whereas the models incorporating the misalignment and incomplete filler exfoliation effects were more efficient. Such models also predicted reduction in the barrier performance of the nanocomposites due to saturation of the polymer matrix with the platelets at a particular filler fraction, an observation which was also experimentally confirmed. Further combinations of these models with each other generated additional insights into the nanocomposite systems such as average aspect ratio, extent of filler platelet randomness, relative platelets distance, shape factor and aggregate thickness etc. As a beneficial alternative, modelling and prediction of the barrier performance of the polymer nanocomposites was also demonstrated using the mixture and factorial design methods. Using factorial design methods, aspect ratio as well as percent randomness of the filler platelets in the nanocomposites could be quantified by knowing beforehand the permeation performance and filler volume fraction. Alternatively, by knowing either the aspect ratio or percent randomness revealed the average permeation behaviour in the nanocomposite of known filler volume fraction.