Novel preparation and properties of polypropylene-vermiculite nanocomposites

A novel approach to the preparation of polymer nanocomposites utilizing a low-molecular-weight reactive modifying reagent has been developed in this study. This is the first report on the fabrication of in situ nanocomposites using maleic anhydride as a reactive reagent that acts both as a modifying additive for the polymeric matrix and as a swelling agent for the silicate. Accordingly, polypropylene-vermiculite nanocomposites with an intercalated or exfoliated structure can be achieved by simple melt mixing of maleic anhydride-modified vermiculite with polypropylene. The nanocomposite structure is evidenced by the absence of vermiculite reflections in the X-ray powder diffraction patterns. Tensile tests show that the tensile modulus and strength of the nanocomposites tend to increase dramatically with vermiculite addition. Such enhancement in mechanical properties results from the formation of intercalated and exfoliated vermiculite reinforcement in the composites. Finally, the thermal properties of the nanocomposites were investigated by means of dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The effects of maleic anhydride addition on the formation of nanometric reinforcement and on the mechanical properties of nanocomposites are discussed.