1. a National Engineering Research Centre of Ultrafine Powder, School of Materials Science and Engineering , East China University of Science and Technology , Shanghai 200237, China
2. b Laboratoire de Rhéologie des Matières Plastiques, FRE CNRS 2396 , Université Jean Monnet , 23 Rue du Docteur Paul Michelon, 42023 St.-Etienne Cedex 2, France