Compressibility and electrical resistivity of carbon nanofiber compacts

The density of carbon nanofiber (CNF) compacts D increases with increasing uniaxial pressure P as P=aD3−b, where a and b are constants. The a-value decreases with decreasing 1/(Ld), where L and d are the average length and diameter of the CNFs, respectively, because the distance between the CNF contacts decreases as the compact is compressed. Moreover, the electrical resistivity of the compressed compact ρ is given as ρ=αD−β, where α and β are constants. The α-value decreases with increasing CNF aspect ratio while β is about 2 regardless of the ratio, which indicates 3-dimensional percolation of CNFs.