LLDPE/TiO2 composites with high UV aging resistance and mechanical properties by controlling the alumina coating on TiO2

Abstract For preparing high performance LLDPE film, the photocatalytic activity and the UV absorption capacity of TiO 2 were regulated by the alumina coating content on the surface of TiO 2 . Alumina‐coated TiO 2 was prepared by the chemical liquid deposition method, and characterized by element analysis, TGA, FTIR, and morphology observation. The alumina coating layer had been proven to covalently bind to the surface of TiO 2 through AlOTi bonds, which formed a continuous and dense coating layer, followed by forming a loose flocculent coating layer with the increase of alumina content. The alumina coating layer could significantly reduce the formation of carbonyl group on the LLDPE chains, and enhance UV aging resistance of LLDPE by inhibiting the photocatalytic activity of TiO 2 . Moreover, the dispersion of alumina‐coated TiO 2 in the LLDPE matrix was improved. Thus, the transmittance of LLDPE/alumina‐coated TiO 2 composites was reduced and the whiteness was improved. Importantly, the continuous and dense alumina coating layer was enough to inhibit the photocatalysis effect of TiO 2 on LLDPE. The further increase of alumina coating content reduced the UV absorption capacity of alumina‐coated TiO 2 and its compatibility with the LLDPE matrix. Therefore, the best alumina coating content on the surface of TiO 2 was 1.46 wt% for preparing high performance LLDPE/TiO 2 composites. Highlights Alumina‐coated TiO 2 with controllable coating thickness was successfully synthesized. LLDPE/alumina‐coated TiO 2 has excellent UV aging resistance and mechanical properties. The photocatalytic activity and UV absorption capacity of TiO 2 could be regulated. 1.46 wt% of alumina coating is the best content for high performance LLDPE/TiO 2 composites.