Abstract
Coextrusion technologies are commonly used to produce multilayered composite sheets of films. Each layer of these composite materials provides a specific end-use characteristic, suc as optical, mechanical or barrier properties. Processing together polymers of different natures may have two consequences : on the one hand, the flow of two adjacent different liquids may give rise to interfacial instabilities which are detrimental to the quality of the final product. On the other hand, the difference of chemical natures of the polymers may lead to delamination of the multilayer film. In order to avoid the latter problem, polymers are compatibilized by introducing a binder between adjacent layers. As a consequence, a non-zero thickness interphase is created between the layers. In this paper, it is theoretically analysed how this interphase may influence the flow stability. As a matter of fact, it is experimentally known that flows of compatible polymers are more stable than those of incompatible systems. Next, a way to optimize the process is proposed.
