Mechanism of Inorganic-organic Surface Modification of Anhydrous Calcium Sulfate Whisker

Anhydrous calcium sulfate whisker (ACSw) was modified by dual-surface modification with sodium silicate solution as inorganic modifer and stearic acid as organic modifier. The samples were characterized by water contact angle (WCA), X-ray diffraction (XRD), field emission scanning electron microscope(FESEM), fourier infrared spectrum (FT-IR), and X-ray photoelectron spectroscope (XPS). The results showed that ACSw surface property changed to Hydrophobic after inorganic-organic modification, while its crystal structure remained unchanged. FT-IR and XPS resutls indicated that -Ca-SiO3 structure was generated firstly on the surface of whiskers after reaction with sodium silicate solution. And then a mixing coating layer containing both -Ca-HSiO3 and -Ca-COOR structures were formed through bonding interaction with stearic acid rather than physical absorption after particle hydrolyzation of -Ca-SiO3 structure.