Combined effect of epoxy functionalized graphene and organomontmorillonites on the morphology, rheological and thermal properties of poly (butylenes adipate-co-terephtalate) with or without a compatibilizer

In this work, clay polymer nanocomposites(CPN) with simultaneous dispersion of graphene and organomontmorillonites (OMt) in a poly (butylene adipate-co-terephthalate) (PBAT) biodegradable matrix were prepared, using the melt-blending technique. Two different OMt were used non polar Cloisite15A and polar Cloisite30B with a composition of 3 mass% as well as epoxy functionalized graphene (EFG) with different compositions (1, 3, 5 mass%). The morphology and thermal properties of OMt/PBAT, EFG/PBAT and OMt-EFG/PBAT nanocomposites were studied. A compatibilizing agent (PBATgMA) was elaborated by grafting maleic anhydride on PBAT chains. The effect of incorporation of this compatibilizer on the different nanofillers dispersion in PBAT matrix was studied. The structure of the nanofillers/PBAT nanocomposites was examined using X-ray diffraction analysis and transmission electron microscopy (TEM). The co-addition of EFG with OMt allowed a better dispersion of these nanofillers and more intercalated structures were obtained. The rheological results showed an increase of the storage modulus G' in the different nanofillers/PBAT nanocomposites, particularly after the co-addition of OMt and EFG. The thermal properties evaluated by TGA were sensibly improved by the association of these nanofillers. From all these results, it can be speculated that a synergism phenomenon between graphene and OMt was produced in the PBAT matrix. However, this phenomenon was reduced after the addition of PBATgMA compatibilizer, probably because of repulsive interactions were produced between this compatibilizing agent and the epoxy functionalized graphene.