TABLE OF CONTENTS Accumulation of waste in the environment has recently stimulated investigations of processes, which can reuse discarded plastics. Since plastics for food packages represent more than 50% of the overall consumption of plastics in Europe, an efficient approach consists of making new packaging materials from recycled plastic packaging. Several techniques are now available. The main difficulty in this field is that discarded plastics may be contaminated by various substances, which may migrate into the food [1]. A solution to this problem could be the incorporation of recycled plastics into multilayer structures, where a layer of virgin polymer is placed between the recycled polymer and the liquid food. The layer of virgin polymer then behaves as a functional barrier, which protects the food from migration of contaminant, at least over a given period of time, which should be known.
Of course, the role of this virgin polymer placed between the food and the recycled polymer is of prime importance. As a matter of fact, the contaminant located in the recycled plastics cannot reach the food before a lag time resulting from its diffusion through the functional barrier. This functional barrier is efficient if this lag time is larger, or at least equal, to the intended shelf life of the food. Various parameters determine the efficiency of the functional barrier, such as the level of contaminant originally in the recycled layer, the nature of the polymer-contaminant couple,...
