Analysis of Microfibril Orientation in Cotton Fibers by Fluorescence Polarization

Microfibril orientation in a cotton fiber surface is measured by the fluorescence polarization method using microphotometry. To serve as a cotton model, drawn nylon fibers are dyed with a high concentration of fluorescent probe and subjected to a twist tester to obtain certain twisting angles, which are then quantitatively determined from the angular distribution of the polarized fluorescence intensity. For naturally dried cotton fibers, this fluorescence polarization analysis shows the twisting angle to be 24.5°. The method also permits analysis of the twisting sense of fibrils in the surface of cotton fibers without needing to untwist them.