Density estimations and comparisons of a fragmented single fiber using X-ray computed tomography

A commercial X-ray computed tomography (CT) apparatus using a quasi-monochromatic beam was utilized for density estimations and comparisons of a fragmented single fiber. The validation of quasi-monochromaticity of the X-ray source was investigated by radiograph measurements. For the case of a transmittance higher than 50%, the contribution of Cu K alpha characteristic X-rays was dominant. To realize a sufficient statistical quality, an attempt to increase the number of averaged voxels was demonstrated using the neighboring slices of the 3D-CT image. A minimum value of the coefficient of variation (CV) was achieved using multiple images rather than using a single image. The observed values of the inverse of the transmitted X-ray intensity (CT value) of the polymers showed a fairly good relationship with their density. An analytical curve derived from measurements of reference samples of known densities could provide the relative density of an unknown fragmented fiber down to the size of 30 mu m in diameter and 35 mu m in length. The CV of the estimated density was from 1.5 to 2%, which was estimated from the CV of CT values. Moreover, the correlation of CT values was improved with the linear absorption coefficient than the density. A better performance of discrimination of polymers including fibers might be realized with the difference of linear absorption coefficients for X-rays.

Automated summary

A commercial X-ray CT apparatus was used to estimate and compare the density of fragmented single fibers using a quasi-monochromatic beam. The quasi-monochromaticity of the X-ray source was validated through radiograph measurements. Increasing the number of averaged voxels in the 3D-CT image improved the statistical quality. The CT values of the polymers showed a good relationship with their density, and an analytical curve derived from measurements of reference samples could accurately determine the relative density of unknown fragmented fibers. The coefficient of variation of the estimated density ranged from 1.5% to 2%. Furthermore, the correlation of CT values was better with the linear absorption coefficient than with density.