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

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 °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 °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 ζ-potential were demonstrated in relation to the type of precursor used for the preparation of ZnO nanoparticles in the structure of hybrid nanocomposite materials.