Preparation and characterization of Kaolinite supported lanthanum-hydroxide and its improvements for natural rubber composites

Abstract

Kaolinite supported lanthanum-hydroxide was successfully prepared via a deposition method and used to improve the mechanical properties of natural rubber (NR) composite. A series of techniques including X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to characterize the samples. The XRD, FT-IR, and EDS results show that lanthanum-hydroxide was successfully loaded on the surface of Kao and may interact with the inner surface hydroxyls. The surface and edge of Kaolinite gradually become rougher, and the lamellar structure had defects due to the loading of lanthanum hydroxide. The resulting material had a uniform dispersion in the natural rubber composite. The scorch time (t10) and curing time (t90) of the filled NR composites decreased simultaneously relative to pure NR, and decreased when compared to that of raw Kao. The tear strength reached at 57.35 kN/m, which increased by 54% relative to that of pure NR. The thermal stability of the prepared composites improved with loading of lanthanum-hydroxide. The reinforcement of the mechanical properties of the filled NR composite is attributed to the fine dispersion of lamellar-like particles in a rubber matrix with restrictions on rubber chain motion via trapping rubber chains and improvements in the incorporation between rubber molecules and filler particles due to the complexation between the rare earth element on the surface of Kao and the double-bond in rubber chains.