Fig. 1 d and e shows the typical TEM images of composite filled with 5 and 10 phr of sepiolite. The particles are relatively well dispersed in the sample and exhibit their characteristic needle shape despite the occurrence of some bundles of microfibers. On the other hand, an orientation of the fibers along a given direction is clearly revealed.When the concentration of sepiolite increases, larger bundles are observed together with a tendancy to form anorthogonal network of fibers (Fig. 1 e).