Physical properties of carbon nanotube sheets drawn from nanotube arrays

• Published in: Carbon (New York) Vol. 50; no. 11; pp. 4175 - 4183
• Main Authors: Pöhls, Jan-Hendrik, Johnson, Michel B., White, Mary Anne, Malik, Rachit, Ruff, Brad, Jayasinghe, Chaminda, Schulz, Mark J., Shanov, Vesselin
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-09-2012; Elsevier
• Subjects: Arrays; Carbon; Chemistry; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; General and physical chemistry; Heat transfer; Materials science; Modulus of elasticity; Nanostructure; Physics; Specific heat; Specific materials; Surface physical chemistry; Tensile strength; Thermal conductivity; Three dimensional; Slippage; Electrical conductivity; Electrical properties; Heat capacity; Carbon nanotubes; Density; Physical properties; Defects; Interfaces; Young modulus; Thermal properties; Resistance; Multiwalled nanotube; Ambient temperature; Thermal conductivity; Models; Thermodynamic properties
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2012.04.067

We report mechanical, thermal, and electrical properties of novel sheet materials composed of multiwalled carbon nanotubes, drawn from a CNT array. At low loading there is some slippage of CNTs but at higher loading tensile strength σ0=7.9MPa and Young’s modulus E=310MPa. The room-temperature thermal conductivity of the CNT sheet was 2.5±0.5Wm−1K−1, giving a thermal conductivity to density ratio of κ/ρ=65Wm−1K−1g−1cm3. The heat capacity shows 1D behavior for T>40K, and 2D or 3D behavior at lower temperatures. The room-temperature specific heat was 0.83Jg−1K−1. The iV curves above 10K have Ohmic behavior while the iV curve at T=2K is non-Ohmic, and a model to explain both ranges is presented. Negative magnetoresistance was found, increasing in magnitude with decreasing temperature (−15% at T=2K and B=9T). The tensile strength, Young’s modulus and electrical conductivity of the CNT sheet are low, in comparison with other CNT materials, likely due to defects. Thermal conductivity is dominantly phononic but interfacial resistance between MWCNTs prevents the thermal conductivity from being higher.