Graphene nanoplatelets (GnP) offer extraordinary good possibilities in order to enhance the permeation properties of nanocomposites. Due to their layered structure and the high aspect ratio paths of gas diffusion through polymer films can be elongated if the nanoplatelets are well dispersed and best exfoliated. But since size and morphology of GnP affects the degree of dispersion different morphology types of GnP have been used for preparation of nanocomposites based on semi-aromatic and aliphatic polyamide. Different compositions of both matrix and GnP materials were melt mixed in a small scale DSM X-Plore microcompounder and subsequently compression moulded. Rheological properties and permeation rate of He have been measured. Furthermore, morphology was investigated using electron microscopy. First results show, that the permeation rate of GnP/PA6-nanocomposites does not significantly correlate with the filling level of GnP but is influenced by the type of polymer. This effect is caused by different interaction between GnP and polymeric matrix and could be confirmed by rheological and morphological investigations.