Influence of the Particle Morphology on the Micro-and Macromechanics of Nano-Reinforced Materials
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Influence of the Particle Morphology on the Micro-and Macromechanics of NanoReinforced Materials Alexander Sarkissov1, Han Meijer1 and Hartmut Fischer Innovative Materials, TNO TPD, P.O.B. 595, 5600 AN Eindhoven, The Netherlands and TU Delft, Aerospace Engineering, Kluyverweg 1, 2629 HS Delft, The Netherlands and 1Eindhoven University of Technology, P.O.B. 513, 5600 MB, Eindhoven, The Netherlands. ABSTRACT This paper describes mechanical properties of polymer-clay nanocomposites with platelet and fibrous like nanoparticles evaluated on a of nano, meso and micro length scale. Platelet reinforced materials were found to display a mixed morphology consisting of intercalated and exfoliated regions. A better dispersion was obtained for fibrous clay nanocomposites where homogeneous distribution of single particles was achieved. The deformation behavior was investigated by in-situ XRD and SEM experiments during drawing; the macro-mechanical characteristics were extracted from tensile tests. The stiffness was found to increase in both platelet and fibrous clay nanocomposites. The presence of intercalated stacks in the latter resulted in a significant reduction in drawability, the better homogeneity of the fibrous clay systems allowed a reasonably high extensions. INTRODUCTION Nanocomposites are materials filled with particles that have at least one dimension in nanometer length scale. One major fact is connected to the filler dimensions, which introduce an essential difference in structure and behavior between conventional composites and nanocomposites. This relates to filler surface area. For one and the same filler volume fraction the surface area of the particles is inversely proportional their dimensions. Hence, the smaller the particle dimensions are, the larger the interface area per unit volume will be. Since many important physical and chemical interactions are governed by surfaces, a nanocomposite material can have substantially different properties from a composite filled with larger particles; influencing its structure on molecular level may change the bulk properties of the matrix. The present paper focuses on polymer-clay nanocomposites, a very active area of research, which resulted in a numerous publications during past two decades. The most popular choice for the filler particles are platelet shaped clays, belonging to the mineral class of layered phyllosilicates1,3. In this study we prepared and investigated nanocomposites based on two different types of filler, namely platelet shaped clay and fibrous clay minerals. The goal of this work was to investigate the structure of the nanocomposites filled with the two differently shaped clays and to compare their mechanical characteristics and deformation behavior. The structure and properties of layered silicates are extensively described in literature4,5. Ion exchange reactions conducted with organic cations permit to increase the distance between the platelets by penetration or in-situ formation of polymer molecules (intercalation) or even to split the
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