Characterization of multiwall carbon nanotubes and influence of surfactant in the nanocomposite processing

• Published in: Carbon (New York) Vol. 41; no. 4; pp. 797 - 809
• Main Authors: Cui, S, Canet, R, Derre, A, Couzi, M, Delhaes, P
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2003; Elsevier Science
• Subjects: A. Carbon nanotubes; C. Raman spectroscopy; Cross-disciplinary physics: materials science; rheology; D. Electrical properties; Exact sciences and technology; Magnetic properties; Materials science; Nanoscale materials and structures: fabrication and characterization; Physics; C. Raman spectroscopy; A. Carbon nanotubes; D. Electrical properties; Magnetic properties; Catalytic reaction; Electrical conductivity; Electrical properties; Nanotubes; Epoxy resin; Crystal growth from vapors; Surfactants; Experimental study; Fabrication property relation; Carbon; Glass transition temperature; Heat treatments; Magnetic susceptibility; Thermal properties; CVD; Multiwalled nanotubes; Nonmetals; Percolation; Nanocomposite; Nickel; Nanostructured materials
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/S0008-6223(02)00405-0

Carbon nanotubes prepared by a classical CVD method with a nickel catalyst have been characterized, then used as conducting anisometric objects dispersed into a polymeric matrix. In a first part, these nanotubes are structurally characterized before and after heat treatments (HTT=1500, 2000, 2500
°C). Diffusion Raman experiments and diamagnetic susceptibility experiments demonstrated their limited graphitized structures.Then, in a second step, a well defined processing way to prepare nanocomposites with a standard epoxy resin is presented. In particular, the use or not of a non-ionic surfactant (Tergitol) to disperse these nanotubes is analyzed. The influence of nanotube contents is examined on the bulk nanocomposite density, the glass transition temperature of the nanocomposites, and the d.c. electrical conductivity behavior. These results demonstrated that the interfacial properties are playing a fundamental role. On one hand, the glass transition temperature is increasing with the nanotube content, and on the other hand, the percolation threshold is found for a rather high critical volumic concentration. Finally, it is demonstrated that a pure geometrical model is not sufficient to explain these behaviors and that a wrapping effect of the organic matrix around the nanotubes has to be considered.