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Nano-silicon dioxide was acquired as colloidal suspension and, although basic characteristics of the particles were provided by the supplier, we examined the preparation further in order to ascertain the particle size distribution, surface charge, crystallinity and purity, so as to conform with current expectations of a minimum level of characterisation prior to toxicological assessment. XRD analysis of the dried nano-SiO2 preparation showed a single peak centered at 26 2θ, which is consistent with amorphous silica, with no evidence for the presence of any crystalline phases of silica or any other impurity. FTIR analysis produced a spectrum containing several absorption bands characteristic of SiO2. 

The peaks at 1105 and 802 cm–1 correspond to antisymmetric and symmetric stretching vibrations of Si–O, respectively, the peak at 477 cm–1 corresponds to the bending vibration of the Si–O–Si bond, and the peaks at 3433 cm–1 and 1641 cm–1 correspond to Si–OH stretching and bending vibrations of the O–H bond of physically adsorbed water.The BET surface area of the nano-silicon dioxide particles measured using dried samples was estimated as 112±0.5 m2/g. Further, the particle surface charge measured in a colloidal suspension using DLS was found to be ?26.5±0.2 mV which indicates the relative electrical stability of the nanoparticles in the original colloidal dispersion.

After Na2SiO3 dilute solution passed through a cation exchange resin to remove Na + ions, mercerized mass fraction was concentrated into about 25% -30% silica sol, after the addition of chemical additives glycerol ethyl acetate was added, followed by stirring of the hydrolysis of the sol appropriate to reduce the pH of the polyvinyl alcohol to make a silica sol having a network structure, easy to form film. Film at 750-850 ℃ pore size distribution between 100-300 nm after heat treatment. Silicon dioxide film during the heat treatment process derived microstructure can be controlled by adjusting the pH value of the silica sol, addition of chemical additives and heat treatment temperature. It discusses the chemical mechanism was formed in nano-silica sol and colloidal silica sol formed by the first body, and the microstructure of the prepared porous silica film morphology change and related physical properties were characterized.


 

 

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