TABLE 1.
COMPARISON OF PHYSICOCHEMICAL CHARACTERIZATION OF BULK MULTIWALLED CARBON NANOTUBES BY THE MANUFACTURER AND AN INDEPENDENT CONTRACT LABORATORY
| Manufacturer (Helix) | Independent (MRL) | |
|---|---|---|
| Purity (TGA) | >95% | >94% |
| Amorphous Carbon (TGA) | <2% | ND |
| Ash (TGA) | <0.2 wt % | ND |
| C (EDX) | 93.4% | 93.75 ± 3.93% |
| O (EDX) | 6.4% | 0.71 ± 0.19% |
| Ni (EDX) | 0.12% | 5.53 ± 3.92% |
| La (EDX) | 0.06% | ND |
| C (ICP-AES) | ND | 99.00% |
| O (ICP-AES) | ND | 0.63% |
| Ni (ICP-AES) | ND | 0.34% |
| La (ICP-AES) | ND | 0.03% |
| Avg. Diameter (TEM) | 10–30 nm | 30–50 nm |
| Length (TEM, SEM) | 0.5–40 μm | 0.3–50 μm |
| BET Surface Area | 40–300 m2/g | 109.29 m2/g |
Definition of abbreviations: BET, Brunauer-Emmett-Teller method; EDX, energy dispersive X-ray analysis; ICP-AES, inductively coupled plasma Auger electron spectroscopy; MRL, Millennium Research Laboratories, Inc.; ND, not determined; SEM, scanning electron microscopy; TEM, transmission electron microscopy; TGA, thermogravimetric analysis.