Advantages of a high-throughput measure of hair fiber torsional properties.

: While the tensile response of fibers of human hair is the most extensively studied mode of mechanical deformation, the properties of hair in different deformation modes remain of interest and can provide valuable insight into the effects of chemical treatments. Previously reported methods for the measurement of fibers in torsional deformation have inherent systematic errors, are low-throughput, and are operator-intensive. This paper presents a new method for the measurement of fiber torsional properties developed to reduce these errors and to improve the efficiency of the technique. This method was designed to be fully automated, requiring no operator input during an experiment, and affording higher sample throughput while improving the ease of use in variable climatic conditions. The new method is compared to a conventional torsional pendulum method for measuring fiber shear modulus, and an evaluation of experimental reproducibility is made using hair and nylon fibers. It was found that the new method provides absolute values for shear modulus similar to those of the pendulum technique, with reduced run-to-run variability between fibers, while enabling larger sample numbers to be explored in shorter times.