Detection of Concentration Inhomogeneity of Carbon Nanotubes in Polyethylene by Spectral-Correlation Method

Abstract

It is shown that the concentration of single-walled carbon nanotubes in polyethylene can be estimated using a spectral-correlation method, which consists of statistical processing of random intensity distributions (speckles) formed by scattering on optical inhomogeneity of the material. The optimal conditions for performing measurements are established, possible causes of errors are determined, and the statistical errors of measurements are estimated. Based on experimental data, expressions are obtained for approximating the dependence of the nanotube concentration on the half-width of the normalized cross-correlation function of the intensity distributions of backscattered radiation at different wavelengths. The possibility of using extrapolation of calibration dependencies for two different physical models (linear and exponential) is considered and the expediency of using a linear model at nanotube concentration above 2% is shown. The concentration of nanotubes in one of the elements of the high-voltage coupling design is evaluated and the possibility of detecting inhomogeneity of the filler concentration in the material is demonstrated.