Analysis of the dispersion state of pitch particles in polymers for nanofiber fabrication by optical microscopy and image processing

Abstract

The polymer blend method is one of the most useful approaches for mass-producing carbon nanotubes and carbon nanofibers. In order to make such nanostructured carbon materials, it is important to understand the dispersion state of the carbon precursor polymer (CPP) in the thermally decomposable polymer (TDP) prior to spinning. In this study, pitch particles have been used as the CPP. Analysis methods of the dispersion of pitch particles in the polymer based on optical microscopy and image processing have been studied. Polished cross-sections of polymers with embedded pitch particles have been observed by polarization microscopy. The microscope images were then transformed into binary images. The centers of gravity of the cross-sections of the pitch particles have been calculated to measure the minimum distances between particles. Fractal analysis has also been applied to estimate the dispersion of the particles. To analyze the spatial frequencies of the particle distribution, two-dimensional fast Fourier transform (2D-FFT) has been applied to the cross-sectional images. Spatial frequency analysis has provided a measure of the distances between particles and of their clustering. The dispersion state of the particles could thereby be gleaned.