Effect of milling atmosphere on stability and surface properties of ZnO/vermiculite hybrid nanocomposite powders

Abstract

The zinc acetate dihydrate and anhydrous zinc chloride were used as precursors for the sonochemical preparation of the zinc oxide/vermiculite and organically modified zinc oxide/vermiculite_chlorhexidine nanocomposite materials. The nanocomposites were mechanically processed via a high-energy ball milling for 30 min at 300 rpm using two types of atmospheres an air or a nitrogen. Changes in temperature and pressure inside the grinding vessels were measured during mechanical processing in an air atmosphere. The ZnO(Cl)/V_30/300 sample reached the highest pressure (1161 mbar) and temperature (30.3 degrees C) in the milling vessels and for the ZnO(ac)/V_CH_30/300 sample the highest temperature difference was measured at the beginning and at the end of the milling (7 degrees C). The phase transformation, chemical composition and particle size of the hybrid nanocomposite materials were investigated using X-ray diffraction method, Fourier-transform infrared spectroscopy, X-ray fluorescence spectroscopy, carbon phase analysis and particle size distribution analysis. Changes in morphology and particle arrangement were characterised using scanning electron microscopy. The effect of mechanical processing in a protective atmosphere on surface properties such as specific surface area, surface conductivity and zeta-potential were demonstrated in relation to the type of precursor used for the preparation of ZnO nanoparticles in the structure of hybrid nanocomposite materials.