Synergism Effect of Montmorillonite and Cellulose Whiskers on the Mechanical and Barrier Properties of Natural Rubber Composites Abdelkader Bendahou, Hamid Kaddami, Eliane Espuche,* Fabrice Gouanve ´, Alain Dufresne* Introduction The properties of polymeric materials can be tailored by the addition of fillers of varying surface chemistry and aggregate size/aspect ratio to suit the application con- cerned. Conceptually, nanocomposites refer to multiphase materials where at least one of the constituent phases has one dimension less than 100 nm. This field has attracted the attention, scrutiny, and imagination of both scientist and industrial communities in recent years. The large interest in the nanoscale range originates from outstanding proper- ties. Enhanced properties can often be reached for low filler volume fraction without detrimental effect on other Full Paper A. Dufresne, A. Bendahou Grenoble Institute of Technology (Grenoble INP) – The International School of Paper, Print Media and Biomaterials (Pagora), BP 65, F38402 Saint Martin d’He `res Cedex, France Fax: (þ33) 4 76 82 69 33; E-mail: alain.dufresne@pagora.grenoble-inp.fr E. Espuche, F. Gouanve ´ Universite ´ Lyon 1, CNRS, UMR 5223, Inge ´nierie des Mate ´riaux Polyme `res, F-69622 Villeurbanne, France Fax: (þ33) 4 72 43 12 49; E-mail: espuche@univ-lyon1.fr A. Bendahou, H. Kaddami Laboratory of Bioorganic and Macromolecular Chemistry, Faculty of Science and Technology, Cadi Ayyad University, Avenue Abdelkrim El Khattabi – BP 549, 40000 Marrakech, Morocco A series of nanocomposite films based on natural rubber (NR), Na þ -montmorillonite (MMT), and cellulose whiskers (W) was prepared, keeping a total filler content equal to 5 wt.-%. In the binary NR/MMT system, small stacks of intercalated montmorillonites were homogeneously dispersed within the polymer matrix whereas they were clearly lying in the vicinity of cellulose whiskers in the ternary NR/MMT/W blends. The effects of MMT and W on mechanical and gas barrier properties of the nanocomposite films were inves- tigated. A significant increase of the rubbery modulus was obtained upon filler addition. The reinforcing effect was particularly important for the nanocomposite film reinforced with 1 wt.-% MMT and 4 wt.-% W. The improvement of the gas barrier properties observed upon filler addition was explained by a tortuosity effect. The calculated tortuosity values indicated that the simultaneous use of MMT and W could greatly slow down the gas diffusion rate in NR. Formation of MMT-W sub- assembly should be responsible for this synergism effect. 760 Macromol. Mater. Eng. 2011, 296, 760–769 ß 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim wileyonlinelibrary.com DOI: 10.1002/mame.201000444