Mechanical and flammability properties of poly(lactic acid)/ poly(butylene adipate-co-terephthalate) blends and nanocomposites: effects of compatibilizer and graphene

Abstract

Poly(lactic acid) (PLA)/polybutylene adipate co-terephthalate (PBAT) blends were prepared by melt blending and compatibilized by glycidyl methacrylate (GMA). The effect of graphene nanoplatelets (GNP) on these compatibilized blends were investigated by incorporating GNP at different content. The formulated blend and nanocomposites were characterized for mechanical, morphological, thermal and flammability properties 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), limiting oxygen index (LOI) and UL-94 respectively. The incorporation of 8 phr GMA into PLA/PBAT (75:25) blend as a compatibilizer results in a significant increase in impact strength (more than 14 times higher) compared to the uncompatibilized blend. Young's modulus and tensile strength of compatibilized PLA/PBAT nanocomposites increased upon addition of GNP and reached maximum values at 4 phr before decreasing slightly. However, impact strength decreased with increasing GNP contents. The thermal stability and the flame retardancy of the GNP reinforced blend nanocomposites were also improved with an increase in nanofiller content and the maximum values for the nanocomposites were achieved at 6 phr. Interestingly, the nanocomposites samples showed a UL-94 rating of V0 at 4 and 6 phr of GNP. Morphological studies using FESEM showed the GNP were evenly distributed and dispersed in the PLA/PBAT nanocomposites. The current methodology to prepare PLA/PBAT blend nanocomposite is an economical way to produce high strength biodegradable polymer which also has good flame retardancy.