Modification of the Filler based on Kaolin and its Use in the Polymer Composites

Department of material technologies and environment, Faculty of Industrial Technologies, I. Krasku 1809/34, 020 01 Púchov, Slovakia

Abstract

Light mineral fillers are the natural inorganic materials of various compositions that have been used in a practical way since the beginning of the rubber industrial processing. Depending on the application, the natural kaolin is often modified by physical processes or by chemical processes (pillaring, adsorption, intercalation, functionalization, acid activation, etc.). It is important to modify kaolin due to improvement of its properties in order to adsorb the inorganic as well as organic molecules. In the introduced study, kaolin from Kaznějov deposit was modified by potassium acetate or dimethylsulphoxide and subsequently functionalized by accelerator dibenzothiazyldisulphide and its last modification was performed by silane treatment. Different techniques, such as the thermal (DTA) and spectral (FTIR) analysis were used to characterize modified kaolin samples. The main aim of the article is to observe the influence of modified kaolin forms on the physico-mechanical properties and structural changes of rubber mixtures. Combined with the carbon black, the given modified kaolin was mixed into a rubber blend in a particular ratio, which was5, 10, 24 phr. The effect of the modified kaolinite on the cure characteristics (minimum torque – M_L, maximum torque – M_H, optimal cure time – t₉₀, scorch time t_s2) and mechanical properties (tensile strength at break – TS_b, elongation at break – E_b and hardness)in sulphur-cured rubber composites was investigated. In images from a scanning electron microscope (SEM), we observed the incorporation of modified forms of kaolin into the matrix of the rubber mixture.