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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

Shear stress as a function of shear rate for PANI suspensions under different DC electric fields: (a) nanofibers, (b) granular. (10 wt%, T = 23°C) [96].
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Figure 7: Shear stress as a function of shear rate for PANI suspensions under different DC electric fields: (a) nanofibers, (b) granular. (10 wt%, T = 23°C) [96].

Mentions: Recently, one interesting way was developed to enhance the yield stress by employing nano-fibrous PANI [96]. The PANI nanofibers were easily synthesized on a large scale by an oxidative polymerization of aniline in an acid aqueous solution without mechanical stirring (see Figure 6). The outer diameter was of 200 nm and length of 1 to 5 μm. The BET surface area of PANI nanofibers was 43 m2/g, which was higher than that (11 m2/g) of granular PANI. After dedoping by immersion in 1 M aqueous ammonia, the PANI nanofibers with decreased conductivity were dispersed into silicone oil with grinding and ultrasonic to form suspensions. Compared to the conventional granular PANI suspension, the nanofiber suspension exhibited larger ER effect. Its shear stress and shear storage modulus were about 1.2 to 1.5 times as high as those of the former. At the same time, the shear stress of the PANI nanofiber suspension could maintain a stable level within the wide shear rate region of 0.1 to 1000 s-1 under various electric fields and the flow curves could be fitted by the Bingham fluid model (see Figure 7a). However, the shear stress of the granular PANI suspension showed a decrease as a function of shear rate to a minimum value, called the critical shear rate (see dot line in Figure 7b), after the appearance of yield stress and then increased again. The flow curves of Figure 7b could not be fitted by the simple Bingham fluid model but could be approximately fitted by the proposed Cho-Choi-Jhon model [97]. These indicated that anisotropic PANI nanofibers not only enhanced the yield stress but also influenced the flow behavior of suspension. In addition, it is interesting that the nanofiber suspension was found to possess better suspension stability compared to the conventional granular suspension when the particle weight fraction was same. No sedimentation occurred for the 15-wt% PANI nanofiber suspension after standing without disturbed for 500 h. This was considered to be related to the small size and large supporting effect of anisotropic nanofibers in suspensions [96].


Electrorheology of nanofiber suspensions.

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

Shear stress as a function of shear rate for PANI suspensions under different DC electric fields: (a) nanofibers, (b) granular. (10 wt%, T = 23°C) [96].
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: Shear stress as a function of shear rate for PANI suspensions under different DC electric fields: (a) nanofibers, (b) granular. (10 wt%, T = 23°C) [96].
Mentions: Recently, one interesting way was developed to enhance the yield stress by employing nano-fibrous PANI [96]. The PANI nanofibers were easily synthesized on a large scale by an oxidative polymerization of aniline in an acid aqueous solution without mechanical stirring (see Figure 6). The outer diameter was of 200 nm and length of 1 to 5 μm. The BET surface area of PANI nanofibers was 43 m2/g, which was higher than that (11 m2/g) of granular PANI. After dedoping by immersion in 1 M aqueous ammonia, the PANI nanofibers with decreased conductivity were dispersed into silicone oil with grinding and ultrasonic to form suspensions. Compared to the conventional granular PANI suspension, the nanofiber suspension exhibited larger ER effect. Its shear stress and shear storage modulus were about 1.2 to 1.5 times as high as those of the former. At the same time, the shear stress of the PANI nanofiber suspension could maintain a stable level within the wide shear rate region of 0.1 to 1000 s-1 under various electric fields and the flow curves could be fitted by the Bingham fluid model (see Figure 7a). However, the shear stress of the granular PANI suspension showed a decrease as a function of shear rate to a minimum value, called the critical shear rate (see dot line in Figure 7b), after the appearance of yield stress and then increased again. The flow curves of Figure 7b could not be fitted by the simple Bingham fluid model but could be approximately fitted by the proposed Cho-Choi-Jhon model [97]. These indicated that anisotropic PANI nanofibers not only enhanced the yield stress but also influenced the flow behavior of suspension. In addition, it is interesting that the nanofiber suspension was found to possess better suspension stability compared to the conventional granular suspension when the particle weight fraction was same. No sedimentation occurred for the 15-wt% PANI nanofiber suspension after standing without disturbed for 500 h. This was considered to be related to the small size and large supporting effect of anisotropic nanofibers in suspensions [96].

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