Effects of ball milling and ultrasonic treatment on the UV shielding performance of illite micro flakes

Abstract Considering the superior film-forming properties and excellent light-reflecting performances on (001) crystal plans of illite, such natural clay mineral could be a potential candidate for novel inorganic UV shielding materials by high-quality purification and particle refinement. In this article, ball milling and ultrasonic treatments were carried out and compared on deep purified illite. The changes of illite during these treatments were characterized by X-ray diffraction (XRD), special surface area (SSA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), UV–vis absorption spectrum, particles size distribution and the point of zero charge (PZC). The results show that compared with ball milling, sonicated illite displays larger particle size and higher surface roughness, since the micro flakes are slowly distorted and separated from original aggregated illite sheets. Further UV–vis transmittance and UV-aging tests reveal that better UV shielding performance of illite is achieved by suitable ball milling treatment, where the illite lamellar aggregates are vertically breaking down into smaller aggregates, and display 34% increased retention ratio of fabric strength than uncoated fabrics under UV irradiation.