Multi-Walled Carbon Nanotubes (MWCNTs)

By Cheap Tubes, INC

Multi-Walled Carbon Nanotubes (MWCNTs) consist of multiple concentric graphene cylinders nested within one another. The spacing between each layer is approximately 0.34 nm, consistent with graphite interlayer spacing. MWCNTs range from 2 nm to 100 nm in outer diameter and can extend to several hundred microns in length. Unlike SWCNTs, MWCNTs are statistically always metallic due to averaging across multiple shells of varying chirality — making them highly reliable for electrical conductivity applications without chirality separation. Physical Properties: - Outer Diameter: 2–100 nm (typical: 10–30 nm) - Inner Diameter: 2–15 nm - Length: 1–100 μm - Specific Surface Area: 200–400 m²/g - True Density: ~2.1 g/cm³ - Bulk Density: 0.03–0.15 g/cm³ - Carbon Purity: 90–99%+ Mechanical Properties: MWCNTs are among the strongest materials ever measured. Tensile strength: 11–63 GPa. Young’s modulus: 270–950 GPa. Compare to high-strength steel at 1–2 GPa tensile / 200 GPa modulus — MWCNTs offer order-of-magnitude improvements at a fraction of the weight. They are also highly flexible and can be bent and twisted without fracturing. Electrical Properties: Electrical conductivity: 10³–10⁷ S/m. In composites, MWCNTs lower the percolation threshold dramatically — loadings as low as 0.1 wt% produce antistatic behavior; 1–5 wt% achieves EMI shielding >20 dB. Current density exceeds 10⁹ A/cm² — approximately 1000× copper. Thermal Properties: Thermal conductivity along the nanotube axis: up to 3,000 W/m·K — exceeding diamond (~2,000 W/m·K) and far surpassing copper (~400 W/m·K). Thermally stable in inert atmospheres to ~2,800°C; oxidation begins at 400–600°C in air. Most commercial MWCNTs — including Cheap Tubes standard grades — are produced by Chemical Vapor Deposition (CVD): a carbon-containing gas (ethylene, methane, or acetylene) is decomposed over a metal catalyst (Fe, Co, Ni) at 600–1200°C. CVD produces controllable diameter, length, and wall number at commercial scale. Selecting Your Grade: Outer diameter — smaller (2–10 nm) = higher surface area, harder to disperse; larger (20–100 nm) = easier to handle. Purity — 90–95% for most applications; >99% for electrochemical and biomedical use. Length — longer (>10 μm) for mechanical reinforcement; shorter (1–5 μm) for thin films. Functionalization — COOH, OH, and NH₂ grades available for specific matrix compatibility. MWCNT pricing from $10–$50/g depending on diameter, purity, length, and functionalization. Contact us for bulk pricing and custom specifications. SDS ships with every order. We offer -COOH (carboxyl), -OH (hydroxyl), -NH2 (amine), -F (fluorine), nitrogen-doped, and oxygen-functionalized MWCNTs. Functional groups improve dispersion in polar solvents and polymers, enable covalent bonding to matrix or biomolecules, and reduce loading required for percolation. Functionalization slightly reduces electrical conductivity along the tube but typically improves overall composite performance because dispersion gains outweigh per-tube losses.