A compound coupling compatibilizer employing coupled use of gamma-(aminopropyl) triethoxy silane (APTS) and maleic anhydride-graft-polypropylene (PPgMA) was synthesized for the preparation of polypropylene (PP)/clay hybrid nanocomposites. The designed PPgMA/APTS compound coupling compatabilizer, through condensation of the amino groups of APTS with the anhydride groups of MA moieties in PPgMA, is capable of forming chemical bonding with the organo clay (org-clay) while maintaining compatibility with the organic PP compartment. Various PPgMA to APTS ratios of these compound coupling compatibilizers were first reacted with clay to form PPgMA/clay masterbatches. The obtained masterbatches were then compounded with PP to produce PP/clay hybrid nanocomposites possessing different characteristics. The composition effects were studied. For org-clay content of 5 wt %, intercalated-exfoliated structure of the nanocomposite could be maintained for better reinforcement. T-d of 484 degrees C was achieved, indicating significant improvement over neat PP (Td was 386 degrees C) in thermal property. The ultimate tensile strength (30% higher than control) and Young's modulus (57% higher than control) measurements also justified the application of the PPgMA/APTS compound coupling compatibilizer in the incorporation of org-clay in PP matrix. The use of the PPgMA/APTS compound coupling compatibilizer can provide design flexibility in manufacturing PP/clay hybrid nanocomposites. (C) 2008 Wiley Periodicals, Inc.