Biodegradable Nanocomposites of Poly(butylene adipate-co-terephthalate) (PBAT) and Organically Modified Layered Silicates

The present article summarizes the development of poly(butylene adipate-co-terephthalate) (PBAT) and organically modified layered silicates nanocomposite using a co-rotating twin screw extruder having a blown film unit. Wide angle X-ray diffraction (WAXD) studies indicated an increase in d spacing of the nanoclays in the bio-nanocomposite hybrids revealing formation of intercalated morphology. Transmission Electron Microscopy (TEM) also confirmed presence of partially exfoliated clay galleries as well as layers of intercalated structures within the PBAT matrix in the nanocomposite. Mechanical tests showed that the nanocomposite hybrids prepared using B109 nanoclay exhibited higher tensile modulus. Functionalization of PBAT matrix upon grafting with maleic anhydride (MA) resulted in further improvement in mechanical properties. The existence of interfacial bonds in grafted bio-nanocomposite hybrids are substantiated using FTIR spectroscopy. Thermal properties of nanocomposite hybrids employing DSC, TGA also revealed improved T_g, T_c and thermal stability over the virgin polymer. Dynamic Mechanical Analysis (DMA) indicated an increase of storage modulus (E′) of PBAT biopolymer with incorporation of nanofiller. The biodegradability of PBAT bionanocomposite hybrids showed an increase in the rate of biodegradability with addition of Na⁺MMT due to hydrophilic nature of the nanoclay.