Papers by Keyword: Electrostriction

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Authors: Keith J. Bowman, R. Moon, E. Drewry, S. Wan, P. Tortorici, Mysore A. Dayananda
587
Authors: Darika Jaaoh, Chatchai Putson, Nantakan Muensit
Abstract: In this work, we present a series of electrostrictive polymer blend that can potentially be used as actuators for a variety of applications. This polymer blend combines an electrostrictive polyurethane with a conductivity polyaniline polymer. The effect of filler content has been investigated. The structures of the blends, the electrical and mechanical properties which affect electrostrictive behavior were studied. The results showed that both dielectric constant and glass transition temperature of the blends increase with increasing polyaniline contents. Moreover, it was noted that space charges distribution and hard-segment domain formation significantly related with electrostrictive coefficient of polymer blend. Therefore, electrostriction behavior in the polymer blends has been demonstrated, and optimal microstructure for electrostriction enhancement has been identified.
697
Authors: Masae Kanda, Kaori Yuse, Daniel Guyomar, Yoshitake Nishi
Abstract: Although their experimental errors can be observed, pure polyurethane (PU) elastomers are one of the most important class of polymers due to some remarkable electromechanical characteristics such as large electric field induced strain, high specific energy and fast speed of response. In order to obtain the large strain at low electric field, a dependence of the solidification condition on strain was investigated for pure polyurethane films. Optimum solidification condition to get thin film with 19 μm thickness remarkably enhanced the strain at high electric field at high electric filed, although they show the low strain at low electric field at low electric filed. The starting point of the convergence occurred at a lower electric field for the solidification condition to get thick film with 150 μm thickness as opposed to for the optimum condition to obtain the thin film with 19 μm thickness. Based on results of crystalline volume fraction and crystalline periodicity, strongly attributed to not only polarization, but also electrostriction, the strain was controlled by the solidification condition. The optimum solidified samples do not have convergence until 20 MV/m. Based on the prediction and experimental results, the electrostriction of PU films depended on its solidification condition.
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Authors: Koji Ogiso, Koichi Hayashi, Akira Ando, Yukio Sakabe
199
Authors: Darika Jaaoh, Chatchai Putson, Nantakan Muensit
Abstract: The purpose of this paper is to investigate an electrostrictive behavior of natural rubber (NR) and NR composites filled with carbon black (CB) nanopowders below percolation threshold. These NR elastomers present advantageous features such as a high productivity, elasticity, and ease of processing. In addition, such materials also exhibit the high induced strain and low young modulus for electrostrictive materials that can be used as actuators and energy harvesting. The NR and all composites were prepared by using solution casting method. The electrostrictive property of the composites was evaluated at low electric field (E 5 MV/m) by measuring the electric field induced strain Sz with the photonic displacement apparatus. The surface morphology of the samples was observed by the atomic force microscopy (AFM) and their electrical properties were analyzed as function of concentration and frequency in a range of 102105 Hz. The results show that the dielectric constant and the dielectric loss decrease when the frequency was increased. Moreover, the dielectric constant and the electrical conductivity strongly increase with increasing the CB contents, relate to interfacial charge distribution. While the dielectric loss slightly increases with increasing filler concentration. The electrostriction coefficient tended to increase with a higher CB loading. In comparison at CB 1 wt%, it was found that the electrostriction coefficient of NR composites is approximately 7 times larger than the pure NR. The NR nanocomposites thus seem to be very attractive for low frequency electromechanical applications.
259
Authors: Juan Zhao, Hui Yuan Zhang, Yin Shun Wang, Hong Wei Liu
Abstract: This paper presents a new method for measuring AC field strength, with application of electrostriction effect of electrostrictive ceramics and technology of fiber Bragg grating. We use electrostriction effect to design the fiber-optic electric field sensor. This device turns the strain of electrostriction material influenced by electric field into the strain of fiber Bragg grating, then wavelength of feedback changes. We can get the strain of electrostriction material through the comparison between initial wavelength and wavelength of feedback, then measurement of electric field strength can be achieved by detecting the strain of electrostriction material. Experiments indicate that fiber-optic electric field sensor based on electrostriction effect is of effective value for measuring electric field strength, and the response of measuring system to AC electric field is linear. We apply an effective method for the research of measuring electric field strength.
235
Authors: Vytautas Samulionis, Juras Banys, Yulian Vysochanskii
Abstract: The paper reviews recent results of ultrasonic and piezoelectric investigation in CuInP2S6 family ferroelectric layered crystals and their solid solutions in the temperature range 100-360 K. It was shown that, Cu substitution by Ag lowers the phase transition temperature. In investigated AgxCu1-xInP2(S,Se)6 crystals above the phase transition (PT) temperature the piezoelectric response was absent and appeared only below the transition. At low temperatures T < 220 K the layered AgxCu1-xInP2Se6 crystals are ferroelectric. Piezoelectric sensitivity in the ferroelectric phase increases with DC field applied along the c-axis, then saturates, and after reversion of voltage the piezoelectric signal decreases, at field near coercive changes sign, and saturates again at high voltage of opposite polarity In the paraelectric phase under external DC electric field, applied along c-axis normal to layers, thin AgxCu1-xInP2Se6 plates can effectively excite and detect ultrasonic waves, due to electrostriction. The same behaviour was observed and in AgxCu1-xInP2S6 crystals. The critical ultrasonic velocity anomalies were observed in the vicinity of PT. In CuInP2S6 crystals with addition of In i.e. indium rich materials the phase transition temperature could be raised to T > 330 K what is important for applications in medical diagnostics ultrasonic transducers. In all these materials the poling conditions were investigated and it was shown that after long time exposing in DC field the piezoelectric sensitivity sufficiently increases and electromechanical coupling constants as high as > 50 % could be obtained.
398
Authors: Nam Ju Jo, Do Hee Lim, Young Min Song, Geong Mi Bark, Won Ki Lee
Abstract: This paper investigated the use of electrostrictive polymers with compliant electrodes as a means of actuator. In many electrostrictive materials, especially polyurethane (PU) can produce large deformation and force because of its low elastic modulus.The electromechanical response is mainly due to Maxwell stress effect and electrostriction effect. When a thin film of dielectric elastomer is applied to an electric field, it will experience Maxwell stress caused by interactions of free charge between the electrodes and electrostriction caused by the reorientation of polar phase in the material. In this work, PU was composed of the soft segment with poly(dimethyl siloxane) (PDMS) and the hard segment with 4, 4’-diphenylmethane diisocyanate. Also the hard segment content of synthesized PU was controlled at 20, 25, 30, and 35wt%. To conclude, mechanical properties increased with the increase in hard segment contents. However actuation test showed that the deformation was decreased as hard segment contents increased.
299
Authors: Vytautas Samulionis, Juras Banys, Yulian Vysochanskii
Abstract: The electromechanical properties of layered, two-dimensional materials of CuInP2S6 family have been investigated. It was shown that, at room temperature, which is above phase transition and under DC bias electric field, these materials behave as a piezoelectric because of electrostriction. In this case, the piezoelectric and electromechanical coupling coefficients are odd functions of the bias field and have a linear dependence on the bias field. The relative changes of ultrasonic velocity are found to have a quadratic dependence on the bias DC field. In bias fields of about 20 kV/m, the values of square of electromechanical coupling coefficient could be high enough (>20%) for longitudinal vibrations in thin plates of investigated CuInP2(S,Se)6 materials in the paraelectric phase. In the ferroelectric phase, the external DC electric field acts as polarizing field and electromechanical coupling coefficients sufficiently increase. At the transitions, the piezoelectric anomalies have been observed.
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