Strain Effect on Dielectricity of Elastic Thermoplastic Polyurethanes
Yubo Wang,
Huali Yang,
Yali Xie,
Xilai Bao,
Lili Pan,
Dan Zhao,
Jinxia Chen,
Mengting Zou,
Tian Tian,
Runwei Li
Affiliations
Yubo Wang
School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201400, China
Huali Yang
CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
Yali Xie
CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
Xilai Bao
CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
Lili Pan
CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
Dan Zhao
CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
Jinxia Chen
CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
Mengting Zou
CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
Tian Tian
School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201400, China
Runwei Li
CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
Dielectric elastomers, such as thermoplastic polyurethanes (TPUs), are widely used as the dielectric layer, encapsulation layer, and substrate of flexible and stretchable devices. To construct capacitors and actuators that work stably upon deformation, it has become urgent to investigate the evolution of dielectricity under stress and strain. However, the lack of effective methods for estimating the dielectric constant of elastomers under strain poses a big challenge. This study reports a device for the in situ measurement of the dielectric constant of TPU under strain. It is found that upon stretching TPU to a strain of 400%, its dielectric constant decreases from 8.02 ± 0.01 to 2.88 ± 0.25 (at 1 MHz). In addition, combined Fourier-transform infrared spectroscopy, the X-ray scattering technique, and atomic force microscopy were utilized to characterize the evolution of the microstructure under strain. The investigation under tensile strain reveals a decreased density and average size of polarized hard domains, along with a tendency of the molecular chains to align in parallel with the tensile stress. The evolution of the microstructures results in a reduction in the measured dielectric constant in TPU.
