| Colloidal antimony pentoxide has been widely used as flame retardant during the past decades due to their larger specific surface area, higher thermal stability, greater coverage ability and transparent compared with other kinds of flame retardants. Meanwhile, colloidal antimony pentoxide has the stronger adsorbing capacity and catalytic ability, and they also can be used as catalyst. So, great effort has been devoted to the synthesis of smaller diameter, higher stability and better dispersed Sb2O5 by many researchers during the past years.This dissertation focuses on the preparation of superfine colloidal antimony pentoxide of water sol and organic sol, and their characterization. The choice of stabilizer and the effects of the amounts of stabilizer on the size and size distribution, the stability of the colloid and the process of making organosols were discussed in detail. The main contents are as follows:Factors including the amounts of the stabilizer affecting size distributions, the shapes and transmission of Sb2O5 and on the conversion rate of Sb2O3 were investigated; the effect of the amounts of hydrogen peroxide on the oxidation reaction rate was studied; the stability and the nucleation mechanism were also studied. Colloidal antimony pentoxide could be easily obtained when n(Sb2O3):n(H2O2)=1:3, t=95℃, m(Sb2O3):m(H2O)=200g/L, n(stabilizer):n(Sb)=0.2-0.5 and the dripping speed of hydrogen peroxide was 0.02mL/s.Size distributions analysis, Transmission electron microscopy, Fourier transform infrared spectra, X-ray diffraction, Differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis and Zeta potential analysis were all used to characterize the colloid.It was indicated that by adjusting the molar ratio of triethanolamine phosphate to antimony from 0.2:1 to 0.5:1, the particles had a very narrow distribution ranging from 3-5 nm; Transmission electron microscopy result indicated that the obtained Sb2O5 nanoparticles were uniform in spherical morphology and with no coagulation; Fourier transform infrared spectra revealed that triethanolamine phosphate was well adsorbed on the surface of Sb2O5 and Sb2O5 had a integrated colloidal structure; X-ray diffraction result showed that the intermolecular interactions between Sb2O5 and the stabilizer played an inhibitory effect on the crystallization of Sb2O5:Zeta potential results showed that in a wide pH region, the colloidal particles were still negatively charged and was very stable; Thermogravimetric analysis revealed that the synthesized colloidal powder was of good thermal stability and did not decompose below 420℃.The organosol of colloidal antimony pentoxide were prepared by the direct method in ethylene glycol with triethanolamine phosphate as stabilizer. Factors affecting the the preparation of colloidal antimony in ethylene glycol were investigated. Experimental results showed that organosol of colloidal antimony could be obtained under the condition that the minimal weight ratio of water to ethylene glycol was 5:9, and that the maximal weight ratio of antimony to dispersion medium was 3:14. The organosols of colloidal was negatively charged and was very stable.The organosols of colloidal antimony pentoxide were also prepared by indirect method with ethanol and DMF as organic solvents respectively. Experimental results showed that organosols of colloidal antimony in ethanol and DMF with a concentration of 20% could be easily obtained by adding a proper amount of lactic acid. In this typical experiment the weight ratio of lactic to ethanol was 0.12 and to DMF was 0.11. |
PDF Full Text Request