The dispersion of nanoclays in nonpolar polypropylene (PP) is difficult without the use of a small fraction (1-3%) of modified grafted PP as a compatibiliser. This work reports the effect of different graft-modified polypropylenes on the dispersion of nanoclays in PP, and thermal stability and flammability of the blends. PP has been compounded in a Brabender compounder with a selection of modified PP polymers as compatibilisers. The grafts include maleic anhydride, N-ethytmaleimide, diethylmaleate, diethyl-p-vinylbenzyl phosphor ate, and acrylic acid-2-[(diethoxyphosphoryl)methylamino] ethyl ester. Films were cast from the blends by compression molding and the nanocomposite structures assessed using X-ray diffraction. Thermal characterization was performed using DSC and TGA, the burning behavior was observed using limiting oxygen index measurements, and cone calorimetry where samples were exposed to 35 kW/m(2) external heat flux. (c) 2008 Wiley Periodicals, Inc.