A new torsion tester based on an electronic autocollimator for characterizing the torsional behaviors of microfibers

Abstract

Torsional properties of single fibers have considerable effects on the performance of fabrics. A new torsion tester with high resolution is developed based on the torsion-balance method and the autocollimation principle for measuring the torsional properties of single fibers. The tester can measure the torque accurately using the torsion wire of known torsional rigidity. The angular displacement of the torsion wire is measured by a non-contact electronic autocollimator. The calibration results show that the maximum torque capability is around 6 × 10−6 N m with a theoretical resolution of about 8 × 10−11 N m. The instrument’s validity is verified by comparing the measurement result with that obtained by a torsion pendulum. Torsion tests on four industrially microfibers, including glass fiber, polyimide fiber, carbon fiber, and gold wire, are performed with the tester, which gives shear moduli 71.0 ± 0.4, 5.6 ± 0.1, 22.6 ± 3.1, and 34.3 ± 0.5 GPa, respectively. Young’s moduli of these fibers are also provided. It is demonstrated that these fibers have a high anisotropy in mechanical properties.

Effects of heat treatments and cross‐linking on the crystal structure and torsional properties of polyester fibers

“…The torsional modulus of the monofilaments shown in Table 1 were calculated according to their torsional properties 15 . The HTPET monofilaments had the highest torsional modulus of 1.1 GPa followed by the PET (0.8 GPa) and PA66 (0.6 GPa) monofilaments, and this phenomenon can be explained by the difference in their rigidity and length of molecular chains 21 .…”

“…Unidirectional torsion tests were executed on a microfiber torsion test device. 15 Five monofilaments of each experimental material were taken for measurement at a loading rate of 720 /min. The effective length of each filament (approximately 4 cm) was measured by a Vernier caliper.…”

“…Unidirectional torsion tests were executed on a microfiber torsion test device 15 . Five monofilaments of each experimental material were taken for measurement at a loading rate of 720°/min.…”

“…The torsional properties of high-performance fibers, such as carbon fibers, PPTA, and polyimide fibers, have been also investigated. [15][16][17][18][19] However, the torsional properties of PET monofilaments have not been yet reported. Therefore, it is necessary to investigate the torsional properties of polyester monofilaments to verify their efficacy as artificial muscle actuators.…”

“…Davis et al 14 reported the torsional and fatigue properties of PET fibers. The torsional properties of high‐performance fibers, such as carbon fibers, PPTA, and polyimide fibers, have been also investigated 15–19 . However, the torsional properties of PET monofilaments have not been yet reported.…”