Preparation of flexible epoxy/clay nanocomposites: effect of preparation method,clay modifier and matrix ductility

In the present report, we studied the effect of different parameters such as preparation methods, different types of modified clay and matrix flexibility on thermomechanical properties of flexible epoxy/clay nanocomposites. The unmodified clay (cloisite Na⁺) was organically modified with decylamines having different number of carbon atoms using an ion exchange method in organo-aqueous solution. The modified clays were characterized by thermogravimetric analysis and X-ray diffraction analysis. Using laboratory modified clay and commercial clay, a series of nanocomposites were made by using solution intercalation and monomer intercalation methods. The dispersion of clay and enhancement in properties of nanocomposites was found to be better for solution intercalation method (use of small amount of solvent) compared to monomer intercalation method. Among all the modified clay, the tetradecylamine-modified clay-based composite showed the effective improvement in the mechanical and dynamic mechanical properties. Addition of 7--9 wt% Cloisite TDA in the epoxy matrix exhibited around 450% and 680% improvement in tensile strength and tensile modulus compared to the neat epoxy. The dispersibility of modified clay in the epoxy matrix was assessed by X-ray diffraction and transmission electron microscopic analysis and the result shows the intercalated morphology of prepared composites. Reinforcing effect was found to be more prominent in a matrix with higher flexibility.