Synergistic Physical Properties of Multiphase Nanocomposites with Carbon Nanotubes and Inorganic Particles
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1056-HH10-01
Synergistic Physical Properties of Multiphase Nanocomposites with Carbon Nanotubes and Inorganic Particles Jan Sumfleth, Montira Sriyai, Luis Prado, Malte H.G. Wichmann, and Karl Schulte Institute of Polymers and Composites, Technische Universität Hamburg-Harburg, Denickestrasse 15, Hamburg, 21073, Germany ABSTRACT Multiphase epoxy-nanocomposites based on multi-wall carbon nanotubes (MWCNT) and inorganic nanoparticles (TiO2) were produced. The rheological, electrical and thermo-mechanical properties were investigated in order to reveal informations about the interparticle interactions between the different types of nanoparticles. TEM-investigations reveal altered microstructures for the multiphase nanocomposites (MWCNT plus TiO2). TiO2 causes changes in the state of dispersion of MWCNT which can lead to an increase of the rheological parameters (e.g. G’). Due to changes in the formation of the percolated MWCNT network during curing, the electrical conductivity is decreased if the concentration of the non-conductive fillers exceeds a critical value. Additional synergistic effects could be found for the glass transition temperature. The presence of nanoparticles leads to a chemical inactivation of reactive groups of the matrix. Thus, the generated interphase between matrix and nanoparticles exhibits a lower curing degree which results in lower thermo-mechanical properties. For the multiphase systems the glass transition temperature is decreased less, due to an inactivation of the surface of the different types of nanoparticles by a self assembly which leads to a higher curing degree of the interphase. INTRODUCTION Nanoparticles are considered to posses a high potential to improve the material properties of polymers. The comprehension and exploitation of this potential are far from being complete, especially for novel nanoparticles, such as carbon nanotubes. The potential differs with different types of nanoparticles. Others, e.g. titania, improve the resistance to ultraviolet light and possess photo catalytic properties. Carbon based particles, e.g. carbon nanotubes (CNT), implicate an electrical conductivity to isolating polymeric materials. Percolation threshold could be found below 0.1 wt.-% with resulting electrical conductivities of up to 10-2 S/m for filler contents of about 0.5 wt.-% MWCNT [1]. In addition, carbon nanotubes can improve the mechanical properties of polymeric systems. An increase of up to 45 % in fracture toughness could be observed for only small amounts of double-wall carbon nanotubes [2]. Due to their high specific surface area and strong interparticle interactions, major challenges in nanocomposite processing have to be met. Amongst other reasons, a lack of industrial applications for carbon nanotube-epoxy composites can be directly related to inadequate dispersion techniques. In recent works we described a highly effective shear mixing process, involving a three roll mill, in order to produce nanocomposites with a superior dispersion of nanoparticles in an epoxy matrix [2,3]. T
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