Adsorption of epichlorohydrin-dimethylamine at the SiC-water interface: A study on wetting, electrokinetics, dispersion stability

In this work, the adsorption of epichlorohydrin-dimethylamine (EPI-DMA) at the SiC-water interface and its influence on the properties of SiC powders were investigated. The adsorption measurements showed that EPIDMA had a high adsorption affinity to the SiC surface and the adsorption equilibrium was reached in 30 min. The Langmuir model and pseudo-first-order model were the best to fit the equilibrium and kinetic data, respectively. The wetting, electrokinetics, dispersion stability of SiC powders modified by different adsorption capacity of EPI-DMA (2.2 mg/g, 2.6 mg/g and 3.4 mg/g) were analyzed and compared. The results showed that with the increase of adsorption capacity of EPI-DMA, wetting properties and dispersion stability of SiC powders were improved. Due to the adsorption of EPI-DMA, the isoelectric point of SiC powders shifted toward alkaline pH and high electrostatic repulsion was obtained at about pH 4. The superior dispersion behavior of SiC powders modified by 3.4 mg/g EPI-DMA in water was attributed to electrosteric stabilization mechanism and small hydrodynamic diameter, leading to low viscosity (0.424 Pa s) of 54 vol% SiC suspension. Furthermore, the conformation of EPI-DMA at the SiC-water interface was proposed.