Study On Preparation Of Nanotubes-Kaolinite And The Preliminary Exploration Of Their Properties

Kaolin is a kind of important industrial materials, to improve the quality is an important direction.Based on this, we used kaolin as raw materials,explored the preparation process from flake kaolin to tubular kaolin. We examined the stability of nanotubes, contrasted and analyzed the viscosity of Nanotubes-Kaolinite, kaolin modified by hot and sour processing and Halloysite-Nanotubes.Finally, we analyzed the effect of Nanotubes-Kaoliniteon on viscosity. TEM/SEM, XRD, TG, FT-IR and BET characterizations were used, Ubbelohde viscometer was used to test viscosityas the structure in low concentration and flat rheometer was used to test rheological.Study found that:the inner and outer diameter of Nanotubes-Kaolinite was in the range of (12-25)nm and (20-40)nm,the length was in the range of (500-1000) nm. Length/diameter was larger, and the production rate was higher. Although Si: Al maintained1:1in layer of nanotubes, they had became disordering along c axis. It was a kind of monodisperse nanotube material, had good acid and thermal stability, its morphology remained intact after2M hydrochloric acid treatment, it had became metakaolinite after heat treatment at600℃for5h, however, their morphology remained nanoscrolls. The surface area was close to Halloysite-Nanotubes, the BET surface area increased from40.25m2/g to70.56m2/g, had good adsorption performance and volume had greatly improved compared with the kaolin.The viscosity of kaolin modified by hot and sour processing has the following rules:viscosity of kaolin modified by hot treat is lower than that of the original kaolin. The amount of surface hydroxyl is the key factor to viscosity of kaolin. Acid treatment could help inner-surface hydroxyl regrow on octahedral,and the adsorption water increased, with the extension of calcining time the number of active aluminum unit increased, so the viscosity of samples would increase after acid treatment. The viscosity of sample300℃calcining9h and then acid treatment is largest, when the concentration is0.01g/ml viscosity value is1.4819cP.Nanotubes-Kaolinite can makes its thixotropy change. The viscosity value of aqueous dispersions in the low shear rate(solid content=12%(w/w)) is6.18X102Pa·s, is larger than that of original kaolin2.15×10-1Pa·s. As the increase of shear rate the viscosity lower, the viscosity value is7.28×10-2Pa·s in the shear rate500s-1, is larger than that of original kaolin6.69×10-3Pa·s, present shear rare phenomenon is false plastic fluid.The greater the surface area of kaolin samples, the larger the opposite charge mutual attraction between particles, length/diameter of Nanotubes-Kaolinite was larger, surface area is bigger, so a bunch of nanotubes arrangement, can form the firm flocculation group like "micelle" shape, have the function of fiber plastic enhance, as a result viscosity increases. Viscosity test results show that when concentration is0.01g/ml slurry viscosity order is:Viscosity value6.7584cP of50%Nanotubes-Kaolinite+50%original kaolin>The max viscosity value1.4819cP of kaolin modified by hot and sour processing>Viscosity value1.3354cP of original kaolin>Viscosity valuel.1944cP of Halloysite-Nanotubes.