On striking variation in impact toughness of polyethylene–clay and polypropylene–clay nanocomposite systems: The effect of clay–polymer interaction

The reinforcement of polyethylene and polypropylene with 4 wt.% nanoclay exhibits a striking variation in impact toughness behavior in the temperature range of −40 to +70 °C under identical processing conditions. The reinforcement of polypropylene with nanoclay increases the impact strength, while polyethylene experiences a decrease in the impact strength. To explain this dissimilar and contrasting behavior, we discuss here the possibility of clay–polymer interaction based on conclusions derived from differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), transmission electron microscopy (TEM), wide-angle X-ray diffraction (WAXD), and Fourier transform infrared spectroscopy (FTIR). The observations suggest the possibility of a strong polypropylene–clay interaction, whereas the polyethylene–clay interaction is weak. The strong interaction in polypropylene–clay system is responsible for significant change in physical and mechanical properties.