Morphology, mechanical and optical properties of transparent BR/clay nanocomposites

Abstract

In this paper, transparent high cis-1,4-polybutadiene (BR)/clay nanocomposites were prepared by directly blending BR, organoclay DK4 (a clay modified with about 40% dimethyl dihydrogenated tallow ammonium chloride (DDAC)) and dicumyl peroxide (DCP). The effects of DCP and DK4 contents on mechanical and optical properties of BR/clay nanocomposites were investigated. The microstructure of these nanocomposites was characterized by wide-angle X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The dispersion dimension of clay particles in BR was quantitatively analyzed by small angle X-ray scattering (SAXS) and intercalated BR/DK4 nanocomposites with typical sandwich structure were prepared. The dispersion of DK4 particles in BR is more uniform than that of pristine clay. The DK4 particles become aggregated in BR with increasing DK4 content. BR/pristine clay composite is opaque due to the poor dispersion of clay particles in BR. However, the BR/DK4 nanocomposites are transparent due to the better dispersion of organoclay DK4. The light transmission of BR/DK4 nanocomposite shows a slight decrease with increasing DCP content. This is attributed to the development of permanent structural inhomogeneities. The transmission decreases while the haze increases with increasing DK4 content when DK4 content exceeds 5 phr. This phenomenon can be attributed to the aggregation of clay particles. The reinforcing effect of DK4 is much better than that of pristine clay in BR matrix. The properties of BR/DK4 and BR/pristine clay composites depend greatly on their microstructure.