Electric-field-induced structuring and rheological properties of kaolinite and halloysite

Abstract

17Electric-field-induced structuring of kaolinite and halloysite particles was studied in respect to 18 their electrorheological (ER) response in silicone oil and in paraffin dispersions. The 19 structural and morphological properties of both clay minerals were studied by XRD, FTIR, 20 SEM, TEM and TGA techniques. The dipolar arrangement induced under application of an 21 electric field was investigated by 2D-WAXS and optical microscopy techniques. The ER 22 response of the samples was measured by both the shear rate controlled method and 23 bifurcation tests. Kaolinite particle dispersions were found to have an improved ER response 24 relative to dispersions of halloysite particles. Finally, the electric currents of these ER fluids 25were measured and the results revealed differences in the current-magnitude between 26 halloysite-and kaolinite-based silicone oil dispersions. 27 28 29

Characterization of halloysite-water nanofluid for heat transfer applications

“…The former corresponds to basal reflection of the clay mineral, which by applying the Bragg's law yields a d-value of 0.74 nm. This result suggests that the Hal is in anhydrous form (Alhuthali and Low, 2013;Lvov et al, 2008;Rozynek et al, 2013;Zhang et al, 2012). The peak at 20.15°2θ can be ascribed to the 020 reflection, while the one at 24.95°2θ is the 002.…”

“…Above 200°C there is a little slope of mass loss due to the removing of water physisorbed at e.g. the micropores of clay Nicolini et al, 2009;Rozynek et al, 2013). The most important mass loss takes place at 490°C, due to the dehydroxylation of the aluminol layers in the Hal.…”

“…Chemical formula of Hal is Al 2 Si 2 O 5 (OH) 4 ·nH 2 O, where n = 0-2. Anhydrous form of Hal (n = 0) has a basal spacing of 0.7 nm, while hydrated form (n = 2) has a basal spacing of 1 nm Lvov et al, 2008;Rozynek et al, 2013). Outer surface of Hal nanotubes consists of tetrahedral siloxane groups (Si-O-Si), whereas inner consists of aluminol groups (Al-OH) (Alhuthali and Low, 2013;.…”

“…Outer surface of Hal nanotubes consists of tetrahedral siloxane groups (Si-O-Si), whereas inner consists of aluminol groups (Al-OH) (Alhuthali and Low, 2013;. Neighborhood of aluminol and siloxane layers provides a highly disordered structure with random dislocations and shifts, which rolls up the multilayer forming the hollow tubular form (Vergaro et al, 2010;Alhuthali and Low, 2013;Rozynek et al, 2013).…”

“…The peak at 20.15°2θ can be ascribed to the 020 reflection, while the one at 24.95°2θ is the 002. The lack of clear peaks in the range from the 020 reflection to 002 suggests a big structural disorder (Rozynek et al, 2013).…”