Preparation, microstructure, and property of silicon rubber/organically modified montmorillonite nanocomposites and silicon rubber/OMMT/fumed silica ternary nanocomposites

Abstract

Five different types of organically modified montmorillonites (OMMT), including Nanomor® I.30P, I.44P, I.24TL, I.34TCN, and I.31PS, were incorporated into silicone rubber (SiR), respectively, by using a melt-blending method. The intercalation structure and spatial dispersion of OMMT in the obtained composites were characterized with wide-angle X-ray diffraction and transmission electron microscopy. The results revealed that the high-polar organic intercalants or silane-coupling agent might play the negative roles in the melt intercalation of SiR into OMMT, and the higher the initial interlayer spacing of the OMMT, the easier the intercalation. The intercalated structure in the SiR/I.44P OMMT nanocomposite has the largest interlayer spacing, and the spatial dispersion of OMMT is also the best. When OMMT loading is low (i.e., less than 10 phr), the dispersion of OMMT is poor. The dispersion of OMMT improves with increasing OMMT dosage, when the loading does not exceed 30 phr. The gas barrier property and the mechanical properties of the SiR are obviously improved by the incorporation of OMMT. The nitrogen gas permeability coefficient of the SiR nanocomposite containing 30 phr OMMT (I.44P) is lower than that of net SiR by 31%. To further improve the dispersion of OMMT in SiR, 20 phr fumed silica (FS) was added to the compound before mixing OMMT for increasing viscosity of the compound and mechanical shearing force during compounding OMMT. The resultant SiR/OMMT/FS ternary nanocomposites exhibit improved dispersion of OMMT and better gas barrier property than the binary counterparts. POLYM. COMPOS., © 2011 Society of Plastics Engineers.