Novel strategic approach for the thermo- and photo-oxidative stabilization of polyolefin/clay nanocomposites

Polyolefin/clay nanocomposites were prepared by melt mixing and their oxidative stability was studied under long-term thermo- and photo-oxidative test conditions in the absence and presence of a modified organo montmorillonite clay (OM-MMt) containing a chemically-bound hindered phenol antioxidant function, (AO)OM-Mt. It was found that nanocomposites based on both polyethylene (PE) and polyethylene-grafted-maleic anhydride (PEgMA) containing the (AO)OM-Mt gave a higher oxidative stability, along with better clay dispersion, compared to analogous PE or PEgMA-based nanocomposites containing an added (free) conventional antioxidant with a similar hindered phenol function (using the commercial hindered phenol Irganox® 1076). These findings can be explained in terms of the ability of the organo-modifier containing the in-built antioxidant function to act locally at the interface between the clay silicate layers and the polymer macromolecules thus contributing to the improved stability of the polymer observed both during long-term thermal- and photo-oxidative treatments.