Phase morphology and physical properties of PP/HDPE/organoclay (nano) composites with and without a maleated EPDM as a compatibilizer

Polypropylene(PP)/high density polyethylene(HDPE) blend nanocomposites were prepared using a twin screw extruder. One commercial organo-montmorillonite (15A) and one maleated rubber (EPDM-MA) served as the reinforcing filler and compatibilizer, respectively. The transmission electron microscopy and X-ray diffraction results confirmed the nano scale dispersion of 15A in the PP/HDPE blend matrix when EPDM-MA was present. The scanning electron microscopy results revealed that EPDM-MA was also an efficient compatibilizer for PP/HDPE blends. Differential scanning calorimetry results indicated that the addition of 15A accelerated the crystallization of PP in the blends, whereas the crystallization of HDPE was hardly influenced. The presence of EPDM-MA slightly influenced the crystallization and melting behavior of the blends/composites. The thermal stability enhancement of PP/HDPE blends after the formation of (nano)composites was confirmed using thermogravimetric analysis. The tensile strength and flexural modulus/strength of PP/HDPE blends increased marginally after adding 15A. These properties declined after the further incorporation of EPDM-MA. Nevertheless, the addition of EPDM-MA greatly increased the impact strength of the blends/composites.