EAPap actuator performance

In the presence of an electric field, the sodium ions surrounded with free water molecules can move to the cathode. Selective ionic and water transport across the polymer under an electric field results in volumetric changes, which in turn lead to bending. When a DC electric field was applied, the cellulose EAPap actuator was bent to the positive electrode, which confirmed the above explanation. The ambient humidity effect on the EAPap actuator performance is further evidence, where ion transport is facilitated when humidity intake is higher. Thus, the actuation principle of cellulose EAPap might be a combination of piezoelectric and ionic migration effects associated with the dipole moment of cellulose material. 

The role of inherent polarization and ionic transport effects in actuation mechanism of EAPap actuators are investigated. To physically investigate the actuation mechanism, several tests are performed. X-ray diffraction (XRD) spectra are compared before and after electrical activation and the possibility of crystalline structure change is observed. Dielectric property measurement indicates a dependence of the dielectric constant on fiber direction, as well as on frequency, humidity, and temperature. Thus, we conclude that piezoelectric effect and ionic migration effect are in the EAPap at the same time associated with dipole moment of cellulose paper ingredients. The amount of these effects may depend on environmental condition. 

To successfully transit cellulose EAPap actuators into these applications, it is crucial to ascertain the actuation principle responsible for the performance parameters. Based on the cellulose structure and our processing of the cellulose-based EAPap, we believe that the actuation is due to a combination of two mechanisms ion migration and piezoelectric effect associated with dipolar orientation. In the remainder of this report, we present experimental evidence of both. 

Further investigation of the actuation behavior of EAPap material, x-ray diffraction (XRD) was tested on the cellophane EAPap sample before and after the electrical actuation. The cellophane EAPap actuator was activated for several hours, then it was removed from the power source and XRD was performed on the surface of the EAPap sample. XRD was measured with an x-ray diffractometer (D/MAX-2500, Rigaku). XRD patterns using Cu-Ka radiation at 40 kV and 30 mA were recorded using 20 = 5-80°. Eigure 18-7 shows the XRD results. Table 18-2 summarizes the XRD peaks before and after the actuation. After actuation, the (110) peak at 12.26° decreased to 12.08° while the (200) peak at 21.64° increased slightly to 22.02°. It is clear that the (110) peak sharpened after the actuation while the (200) peak was changed to blunt. This confirms that the first peak increased and the second peak decreased. 

In this report, cellulose has been investigated as a smart material. Various kinds of paper fibers were tested, and cellulose paper was found to be a good candidate for EAPap. The performance of cellulose EAPap actuators was investigated. Regenerated cellulose exhibited a remarkable displacement output. When 0.25 V/pm... 

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