111. Stearic Acid-Modified γ-Al₂O₃ Particles for Dispersion Properties

It is difficult for γ-Al₂O₃ particles to disperse due to a mismatch in the density of dispersion medium, which leads to agglomeration and sedimentation of the γ-Al₂O₃ particles. In the study, we use the orthogonal experiments of three factors and three levels to analyze the influence of related factors on modification effect and seek the most suitable modification conditions. In the experiment, the stearic acid (SA) was used to modify the surface of the γ-Al₂O₃ particles. γ-Al₂O₃ particles before and after surface modification were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermal gravity analysis (TG) and dynamic light scattering (DLS). The FTIR spectra showed that SA had been successfully grafted onto the surface of the γ-Al₂O₃ particles. Thermal gravity analysis showed that the coated amount of SA is 4.41 %. SEM shows that the agglomeration of Al₂O₃ particles after modification was reduced. DLS shows Al₂O₂ particles after modification have smaller particle size and more narrow distribution and better dispersion property. Determination of Oil-Wet Coefficient show Al₂O₃ particles after modification hydrophilic strengthen. Therefore, the SA-modified Al₂O₃ particles demonstrated better dispersion properties. Sedimentation test showed that the modified γ-Al₂O₃ particles had better suspension stability than the non-modified γ-Al₂O₃ particles.