Polypropylene-organoclay nanocomposites were prepared by melt processing via twin-screw extrusion of three components: PP, maleic anhydride modified polypropylene oligomers (PPgMA) and clays modified by octadecylammonium for the purpose of evaluating the effect of the amount of the grafted compound of the PP on the mechanical properties. Two ways were used to compatibilize the PP and nanoclay. First, varying the PPgMA percentage on the nanocomposite, and secondly its degree of functionalization. The rheological and mechanical properties were studied in relationship to the microstructure of the nanocomposites varying both parameters. X-ray diffraction was used to detect the formation of nanocomposites and the transmission electron microscopy (TEM) was used to characterise the dispersion of the organoclay.