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*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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].

Original languageEnglish
Title of host publicationElectroactive Polymer Actuators and Devices (EAPAD) XXIV
EditorsIain A. Anderson, John D. W. Madden, Herbert R. Shea
PublisherSPIE
ISBN (Electronic)9781510649590
DOIs
Publication statusPublished - 2022
Externally publishedYes
EventElectroactive Polymer Actuators and Devices (EAPAD) XXIV 2022 - Long Beach, United States
Duration: 2022 Apr 62022 Apr 11

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume12042
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceElectroactive Polymer Actuators and Devices (EAPAD) XXIV 2022
Country/TerritoryUnited States
CityLong Beach
Period22/4/622/4/11

Keywords

  • Artificial muscle
  • Entropic elasticity
  • Polymer fiber
  • Thermal expansion
  • Twisted and coiled fiber actuator

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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