Structural Modification Of Montmorillonite And Interfacil Enhancement Of Clay/Rubber Nanocomposite

In order to realize the full potential of performance of the nanocomposites, a covalent interface between clay and rubber must be constructed and a high dispersion of clay within the rubber matrix must be obtained. This study was carried out with the interface and dispersion as the basis; and the work consisted of two parts-structural modification&interlamellar silylation of montmorillonite, and preparation of highly dispersed clay/rubber nanocomposite with excellent performance.In the first part of the thesis (Chapter3), hydrochloric acid with different concentration was applied to treat clay to modify structure followed by immobilization of y-methacryloxy propyl trimethoxysilane (KH570) molecules by covalent grafting with surface and interlayer silanol groups. The effects of acid on the microstructure of clay and the changes in properties and structure of acid-treated clay and functionalized clay were investigated. Results showed that the dissolution of tetrahedral and octahedral Al of clay occurred at the same rate in acid solution and acid treatment favored the enrichment of active hydroxyl groups at the edges and faces of clay platelets, leading to an increase in the grafted amount of organosilane. It was confirmed that the grafting reaction took place to form silane oligomer coverage on the layers result in a highly disordered structure and a dramatic increase of surface area.In the second part of the thesis (Chapter4), two methods were applied to prepare clay/rubber nanocomposites modified by silane:(1) silane-grafted clay suspension and SBR latex were co-coagulated by latex compounding method and nanocomposite was prepared after vulcanization;(2) acid-treated clay and SBR were compounded, silane was added into the compound on the mixing mill and the grafting reaction happened during curing, nanocomposite was prepared. The dispersion state of clay in rubber matrix and the mechanical properties of nanocomposite were investigated. Results showed that during vulcanization a chemical bridge between clay and rubber matrix through silane molecules was built, layers aggregation was effectively prevented and the interfacial interaction was remarkably improved. Highly dispersed clay/rubber nanocomposite with excellent performance was obtained. Both the significantly improved dispersion of MMT and establishment of covalent interface were important for improving the ultimate performance of the nanocomposites.