A novel approach to characterize torsional property of single fiber

A novel approach to evaluate the torsional property of single fiber filament was established based on a self-designed apparatus. The number of torsion turns obtained from the direct torsion failure test was used to characterize the torsion bearing capacity of single fiber. Three types of carbon fibers were investigated, namely, T700S, T300, and M40. The number of torsion turns decreases in the order of T700S, T300 and M40, which agrees well with the elongation at break, implicating that the fibers with higher toughness provide better torsional property. The effect of fiber sizing agent on the torsion characteristics was also examined. It has been found that fiber sizing agent has no influence on the single fiber torsional properties. The effect of torsion speed was also considered. Results showed that the number of torsion turns for carbon fiber T300 decreases with increasing torsion speed, and levels off beyond the torsion speed of 50 r/min.