Mechanical and flammability properties of graphene reinforced compatibilized poly(lactic acid) / poly(butylene adipate-co-terephthalate) nanocomposites

Abstract

Graphene nanoplatelets (GNP) reinforced, glycidyl methacrylate (GMA) compatibilized blends of PLA/PBAT nanocomposites were prepared by melt extrusion followed by injection molding. GMA act as compatibilizer with contents of 3, 5 and 8 parts per hundred (phr) were added to the base formulation PLA/PBAT (75/25 weight percent). GNP reinforced nanocomposites 2, 4 and 6 phr were prepared and characterized by using universal testing machine, impact tester, field emission scanning electron microscope (FESEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), limiting oxygen index (LOI) and UL-94V. Compatibilization of the blends with 8 phr GMA results in a blend with highest notched Izod impact strength. The impact strength was enhanced more than 10 times compared to the uncompatibilized blend. Tensile and flexural strengths of test specimens were evaluated and the results revealed that with the presence of GNP nanoplatelets, moderate improvement in stiffness and strength of the nanocomposites were observed. The morphological studies from FESEM micrograph showed the GNP nanoplatelets were embedded and reasonably evenly distributed in the polymer matrix. The thermal stability based on TGA results and the flame retardancy of the GNP reinforced nanocomposites were generally improved with increasing nanofillers content with the optimum at 6 phr. The FTIR analysis did not show chemical interaction between GNP nanoplatelets and polymer matrix although the mechanical and thermal properties of the GNP reinforced nanocomposites were moderately improved.