Combined effect of nanoclay and alumina addition on structure, TGA, DMA characteristics of nanoclay, and alumina-filledpolypropylene nanocomposites

A series of PP-MA-g-PP/MA-g-EPR - clay/alumina - titanate nanocomposites with varied proportions of clay and alumina composition, maintaining the matrix modifier and coupling agent composition constant, were prepared by melt blending. Two different modifiers, maleic anhydride (MA)-grafted polypropylene (PP) and MA-grafted EPR, along with coupling agent are used in order to improve the dispersibility of reinforcing filler. The resultant nanocomposites in presence and absence of matrix modifiers and coupling agent were compared for their dynamic mechanical and thermal properties. The morphology of nanocomposites was studied by X-ray diffraction and high-resolution scanning electron microscopy. Most of the cases, the combination of intercalated and exfoliated nanocomposites was obtained. Particularly for the sets with titanate, coupling agent showed better dispersion of reinforcing filler. The resultant nanocomposites showed an increase in storage modulus and tan delta values in presence of coupling agents. This reflected as an improvement in load-bearing capacity and stiffness of nanocomposite in dynamic mechanical analysis studies. The matrix modifiers and coupling agent very effectively influenced the thermal transition of nanocomposites. Blending of matrix modifier and addition of reinforcing filler reduced the melting temperature of nanocomposites because of reduction of crystallinity matrix in presence of filler and modifier, whereas incorporation of coupling agent brought the melting temperature back the almost original value of virgin PP. The thermal stability of PP improved 16-37 degrees C by incorporation of reinforcing filler along with coupling agent.