tailieunhanh - ADVANCES IN DIVERSE INDUSTRIAL APPLICATIONS OF NANOCOMPOSITES_2

Tham khảo sách 'advances in diverse industrial applications of nanocomposites_2', kỹ thuật - công nghệ, hoá học - dầu khí phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 13 Polymeric Nanoclay Composites Hamid Dalir Rouhollah D. Farahani Martin Lévesque and Daniel Therriault École Polytechnique de Montreal Canada 1. Introduction Traditionally polymeric materials have been filled with synthetic or natural inorganic compounds in order to improve their properties or simply to reduce cost. Conventional fillers are materials in the form of particles . calcium carbonate fibers . glass fibers or plateshaped particles . mica . However although conventionally filled or reinforced polymeric materials are widely used in various fields it is often reported that the addition of these fillers imparts drawbacks to the resulting materials such as weight increase brittleness and opacity Alexandre Dubois 2000 Fischer 2003 Lagaly 1999 Giannelis 1996 Varlot et al. 2001 . Nanocomposites on the other hand are a new class of composites for which at least one dimension of the dispersed particles is in the nanometer range. Depending on how many dimensions are in the nanometer range one can distinguish isodimensional nanoparticles when the three dimensions are on the order of nanometers nanotubes or whiskers when two dimensions are on the nanometer scale and the third is larger thus forming an elongated structure and finally layered crystals or clays present in the form of sheets of one to a few nanometers thick and hundreds to thousands nanometers in extent Alexandre Dubois 2000 Fischer 2003 Lagaly 1999 Giannelis 1996 . Among all the potential nanocomposite precursors those based on clay and layered silicates have been most widely investigated probably because the starting clay materials are easily available and because their intercalation chemistry has been studied for a long time Gorrasi et al. 2002 . Polymer-layered silicate nanocomposites which are the subject of the present contribution are prepared by incorporating finely dispersed layered silicate materials in a polymer matrix Fischer 2003 . However the nanolayers are not easily dispersed in