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Electrorheology of nanofiber suspensions.

Yin J, Zhao X - Nanoscale Res Lett (2011)

Bottom Line: Recent researches of using nanoparticles as the dispersal phase have led to new interest in the development of non-conventional ER fluids with improved performances.In this review, we especially focus on the recent researches on electrorheology of various nanofiber-based suspensions, including inorganic, organic, and inorganic/organic composite nanofibers.Our goal is to highlight the advantages of using anisotropic nanostructured materials as dispersal phases to improve ER performances.

View Article: PubMed Central - HTML - PubMed

Affiliation: Smart Materials Laboratory, Department of Applied Physics, Northwestern Polytechnical University, Xi'an 710129, China. jbyin@nwpu.edu.cn.

ABSTRACT
Electrorheological (ER) fluid, which can be transformed rapidly from a fluid-like state to a solid-like state under an external electric field, is considered to be one of the most important smart fluids. However, conventional ER fluids based on microparticles are subjected to challenges in practical applications due to the lack of versatile performances. Recent researches of using nanoparticles as the dispersal phase have led to new interest in the development of non-conventional ER fluids with improved performances. In this review, we especially focus on the recent researches on electrorheology of various nanofiber-based suspensions, including inorganic, organic, and inorganic/organic composite nanofibers. Our goal is to highlight the advantages of using anisotropic nanostructured materials as dispersal phases to improve ER performances.

No MeSH data available.


Related in: MedlinePlus

Dielectric spectra for the suspensions of titania nanoparticles (square points), 250°C-heated Na-titanate nanofibers (circle points), and 250°C-heated H-titanate nanofibers (triangle points) [73].
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Figure 3: Dielectric spectra for the suspensions of titania nanoparticles (square points), 250°C-heated Na-titanate nanofibers (circle points), and 250°C-heated H-titanate nanofibers (triangle points) [73].

Mentions: A positive ER effect of nanofiber suspensions was reported by the current authors by employing titanate nanofibers as dispersed phase [72,73]. Titanate nanofibers were synthesized by a hydrothermal reaction of titania nanoparticles in high-concentration alkali solution following the Kasuga's report [74]. Titanate nanofibers were uniform nanotube-like morphology with outer diameter of 10 nm and length about 100-200 nm after ultrasonic (see Figure 1). High-resolution transmission electron microscopy (TEM) image (Figure 1d) and selected area electron diffraction (ED) (inset in Figure 1d) showed that the nanotubes consisted of the roll multilayered structure with an inner diameter of 3 nm. The energy-dispersive X-ray spectroscopy analysis showed the titanate nanofibers contained Na, Ti, and O elements. ER properties of suspension of titanate nanofibers in silicone oil were investigated by a steady shear viscosity. Compared to the suspension of titania nanoparticles, the suspension of nanofibers showed higher yield stresses (see Figure 2). At the same time, the alkali-ions intercalated in the interlayer of nanofibers were found to be important to the ER effect of titanate nanofibers. Removal of alkali-ions by acid-treatment did not destroy the nanofiber morphology (see Figure 1e) but weakened ER effect. According to the dielectric spectra analysis (see Figure 3), the decrease of ER effect was considered to be due to the degradation of dielectric property. However, it was noted that the ER effect of nanofiber suspension after removal of alkali-ions was higher than that of pure titania nanoparticle suspension. In particular, after 400°C calcination, the acid-treated nanofibers almost possessed the similar crystal structure and slightly higher dielectric constant compared with pure titania nanoparticles, but the ER effect of the former was still higher than that of the latter. This indicated that the anisotropic nanofiber structure played a role in improving the ER performance. In addition, the ER effect of titanate nanofiber suspension increased with increasing temperatures, which was in accordance with the improving dielectric properties. Another advantage of titanate nanofiber suspension was its lower particle settling rate compared to the conventional granular titania suspension.


Electrorheology of nanofiber suspensions.

Yin J, Zhao X - Nanoscale Res Lett (2011)

Dielectric spectra for the suspensions of titania nanoparticles (square points), 250°C-heated Na-titanate nanofibers (circle points), and 250°C-heated H-titanate nanofibers (triangle points) [73].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211318&req=5

Figure 3: Dielectric spectra for the suspensions of titania nanoparticles (square points), 250°C-heated Na-titanate nanofibers (circle points), and 250°C-heated H-titanate nanofibers (triangle points) [73].
Mentions: A positive ER effect of nanofiber suspensions was reported by the current authors by employing titanate nanofibers as dispersed phase [72,73]. Titanate nanofibers were synthesized by a hydrothermal reaction of titania nanoparticles in high-concentration alkali solution following the Kasuga's report [74]. Titanate nanofibers were uniform nanotube-like morphology with outer diameter of 10 nm and length about 100-200 nm after ultrasonic (see Figure 1). High-resolution transmission electron microscopy (TEM) image (Figure 1d) and selected area electron diffraction (ED) (inset in Figure 1d) showed that the nanotubes consisted of the roll multilayered structure with an inner diameter of 3 nm. The energy-dispersive X-ray spectroscopy analysis showed the titanate nanofibers contained Na, Ti, and O elements. ER properties of suspension of titanate nanofibers in silicone oil were investigated by a steady shear viscosity. Compared to the suspension of titania nanoparticles, the suspension of nanofibers showed higher yield stresses (see Figure 2). At the same time, the alkali-ions intercalated in the interlayer of nanofibers were found to be important to the ER effect of titanate nanofibers. Removal of alkali-ions by acid-treatment did not destroy the nanofiber morphology (see Figure 1e) but weakened ER effect. According to the dielectric spectra analysis (see Figure 3), the decrease of ER effect was considered to be due to the degradation of dielectric property. However, it was noted that the ER effect of nanofiber suspension after removal of alkali-ions was higher than that of pure titania nanoparticle suspension. In particular, after 400°C calcination, the acid-treated nanofibers almost possessed the similar crystal structure and slightly higher dielectric constant compared with pure titania nanoparticles, but the ER effect of the former was still higher than that of the latter. This indicated that the anisotropic nanofiber structure played a role in improving the ER performance. In addition, the ER effect of titanate nanofiber suspension increased with increasing temperatures, which was in accordance with the improving dielectric properties. Another advantage of titanate nanofiber suspension was its lower particle settling rate compared to the conventional granular titania suspension.

Bottom Line: Recent researches of using nanoparticles as the dispersal phase have led to new interest in the development of non-conventional ER fluids with improved performances.In this review, we especially focus on the recent researches on electrorheology of various nanofiber-based suspensions, including inorganic, organic, and inorganic/organic composite nanofibers.Our goal is to highlight the advantages of using anisotropic nanostructured materials as dispersal phases to improve ER performances.

View Article: PubMed Central - HTML - PubMed

Affiliation: Smart Materials Laboratory, Department of Applied Physics, Northwestern Polytechnical University, Xi'an 710129, China. jbyin@nwpu.edu.cn.

ABSTRACT
Electrorheological (ER) fluid, which can be transformed rapidly from a fluid-like state to a solid-like state under an external electric field, is considered to be one of the most important smart fluids. However, conventional ER fluids based on microparticles are subjected to challenges in practical applications due to the lack of versatile performances. Recent researches of using nanoparticles as the dispersal phase have led to new interest in the development of non-conventional ER fluids with improved performances. In this review, we especially focus on the recent researches on electrorheology of various nanofiber-based suspensions, including inorganic, organic, and inorganic/organic composite nanofibers. Our goal is to highlight the advantages of using anisotropic nanostructured materials as dispersal phases to improve ER performances.

No MeSH data available.


Related in: MedlinePlus