Abstract: Hydrophobic zinc borate (Zn2B6O11·3H2O) was prepared via a onestep wet synthesis from zinc sulfate and sodium borate, with oleic acid as the surfactant. The morphology and hydrophobic property of the products were analyzed by means of Xray diffraction, Fourier transform infrared spectroscopy, contact angle analyzer, and scanning electron microscope. It indicated that the diameter and thickness of the products were 1～2 μm and 0.1 μm, respectively; the water contact angle was 105.1 °. The prepared hydrophobic zinc borate was introduced into EVA/Mg(OH)2 composites as a flame retardant. A synergetic effect was observed, the value of limited oxygen index reached 38.5 %, and the mechanical properties were only moderately decreased.

Key words: zinc borate, surface modification, hydrophobic property, flame retardant