Neutrons et matériaux : introduction

Schweizer, J.

doi:10.1051/jp4:20030001

Cited by 1 publication

(1 citation statement)

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“…where (Dq) 2 , given in m -4 , is a constant related to the difference in contrast between the TiO 2 and PDMS [13], and S/V is the surface per volume unit ratio. The specific area denoted S S (given in m 2 /g) is connected to S/V through the relation: Iq versus q.…”

Section: Characterization Of the Nanoporous Tio 2 Particlesmentioning

confidence: 99%

Acetylacetone stimulus effect on electrorheological properties of TiO2 aggregated nanoparticles

2013

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We present experimental results on electrorheological behavior under an ac electric field, and dielectric properties of colloidal suspensions composed of aggregated titanium dioxide nanoparticles dispersed in insulating PDMS silicon oil, as a function of adsorbed acetylacetone (Acac) dipolar molecules on TiO 2 surface. The results show that the elastic modulus G 0 of TiO 2 -Acac/ PDMS ER fluid decreases when the electric field frequency is increased gradually from 10 to 10 4 Hz. In the range of tested electric field frequencies, we observe that the dielectric properties are given essentially by an interfacial polarization which is maximal at low frequency. At low frequency (t = 10 Hz), G 0 increases with the increasing Acac/TiO 2 surface coverage h from 0 to 0.45, due to the high polarization of the particles caused by the increase of the charge carriers that move to the interface between TiO 2 particles and the insulating medium. For h = 0.35, G 0 reaches 1.80 MPa which is 3.6 times greater than that of pure TiO 2 /PDMS ER fluid. However, G 0 decreases by increasing h beyond 0.45; in such cases, the mismatch on dielectric constant and conductivity between dispersed phase (TiO 2 ) and insulating medium (PDMS) begins to fall as h increases because of the increase of Acac dipoles remaining free in PDMS. The performance of TiO 2 -Acac/ PDMS ER fluid at low frequency was validated by a reversibility test where elastic modulus G 0 increases dramatically and returns to its initial state as soon as several cycles of a switching electric field were applied between 0 and 1 kV/mm successively.

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Section: Characterization Of the Nanoporous Tio 2 Particlesmentioning

confidence: 99%