Solid state NMR investigation of polypropylene/Brazilian clay blending process

Nanocomposites formed by polypropylene/clay without change to either polymer or clay were prepared using two methods. In the first method, molten polymer was pressed for 15 min and then cooled at room temperature. In the other method, a plastograph mixer (Haake) was used with a twin screw operating at the melting temperature of polypropylene for 10 min. The nanocomposites produced had their crystalline and molecular structures investigated by nuclear magnetic resonance (NMR) spectroscopy. To evaluate the changes in the polymer morphology the nucleus chosen was 13C. 29Si and 27Al were used to observe the changes in the clay structure. From the NMR spectra, it was found that the crude clay interferes in the polypropylene crystallization process due to a specific interaction between both components. These changes were observed in both chemical shift and line width of the silicon and aluminum nuclei spectra of the nanocomposite, when compared to clay.