A series of HDPE/MMT nanocomposites with different proportions of compatibilizers, PE-g-MAH (AC573A and 5TP409/E) were prepared in a counter rotating twin screw extruder. The effect of nanoclay loading, compatibilizer type and amount was examined. The work was carried out using a specific grade of HDPE recommended for blow-moulding applications and modification of the same by blending with selected polymer and nanofiller to achieve the desired properties. The composition containing higher percentage of nanoclay showed improvement in mechanical properties. About 17% in tensile modulus and about 20% increase in flexural modulus were observed with high-viscous compatibilizer. The dispersion behaviour of nanoclay in PE matrix was studied using X-ray diffraction and transmission electron microscopy. It was clear from WXRD that in all nanocomposite samples, the peaks were shifted to lower 2 theta values implying that the d-spacing increases and that intercalation occurred. Low molecular weight compatibilizer PE-g-MA resulted in better intercalation than high molecular weight compatibilizer. It was observed that in the case of 5% AC573A loading, there was slight decrease in d-spacing value which indicated that some exfoliation also occurred in nanocomposite. Nanocomposite containing PE-g-MAH is higher concentration gives better dispersion than at low concentration. TEM results show that PE-g-MAH (AC573A) at 5% loading is more efficient as compatibilizer (not many aggregates seen) than other compositions. (C) Koninklijke Brill NV, Leiden, 2010