The origin of contraction of twisted polymer fiber muscles: whether the cause is entropic elasticity or thermal expansion

Daisuke Kimura; Toshihira Irisawa; Kentaro Takagi; Kenji Tahara; Daichi Sakurai; Haruhiko Watanabe; Wataru Takarada; Masatoshi Shioya

doi:10.1117/12.2612843

20 April 2022 The origin of contraction of twisted polymer fiber muscles: whether the cause is entropic elasticity or thermal expansion

Daisuke Kimura, Toshihira Irisawa, Kentaro Takagi, Kenji Tahara, Daichi Sakurai, Haruhiko Watanabe, Wataru Takarada, Masatoshi Shioya

Author Affiliations +

Proceedings Volume 12042, Electroactive Polymer Actuators and Devices (EAPAD) XXIV; 120420P (2022) https://doi.org/10.1117/12.2612843
Event: SPIE Smart Structures + Nondestructive Evaluation, 2022, Long Beach, California, United States

Abstract

In recent years, polymer fiber actuators obtained by twisting polymer fibers have attracted much attention. These actuators actuate due to the reversible axial thermal contraction and radial thermal expansion of untwisted fibers. In this study, thermal contraction of the two polyamides, PA6 and PA610, fibers were investigated. The fiber length of both fibers changed reversibly in response to temperature change, but there was no initial load dependence on the amount of contraction. These results indicate that this thermal contraction is not due to the entropic elasticity effect seen in rubber. In addition, the thermal contraction was larger for PA610, which has a larger thermal expansion coefficient in the amorphous state. This suggests that the thermal expansion of the amorphous state was converted by its fiber structure into expansion in the diameter direction and contraction in the fiber axial direction [Kimura et al., Sens. Actuators B Chem., 2021].

Conference Presentation

Citation Download Citation

Daisuke Kimura, Toshihira Irisawa, Kentaro Takagi, Kenji Tahara, Daichi Sakurai, Haruhiko Watanabe, Wataru Takarada, and Masatoshi Shioya "The origin of contraction of twisted polymer fiber muscles: whether the cause is entropic elasticity or thermal expansion", Proc. SPIE 12042, Electroactive Polymer Actuators and Devices (EAPAD) XXIV, 120420P (20 April 2022); https://doi.org/10.1117/12.2612843

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