Morphology, thermal and barrier properties of green nanocomposites based on TPS and cellulose nanocrystals

The overall objective of this study was to fabricate and characterize the properties of nanocrystalline cellulose/thermoplastic starch (TPS)-based nanocomposites. For the isolation of cellulose nanocrystals (CNCs) from cotton, it is subjected to alkaline treatment followed by acid hydrolysis. Then these CNCs were dispersed in TPS using a Fluko high-shear mixer in varying proportions, and the films were casted out of these nanocomposites using solvent casting technique. The CNCs were analyzed by transmission electron microscopy (TEM), wide-angle x-ray diffraction (WAXD) and Fourier transform infrared spectroscopy. TEM images of cellulose crystals extracted from cotton linters confirmed its nanodimensions with a size of 20–50 nm. WAXD results showed 2 θ peaks at 14.8°, 16.7° and 22.5° characteristic of the cellulose type-I crystalline structure. The films were analyzed by WAXD, scanning electron microscopy, thermogravimetric analysis (TGA) and moisture barrier properties. There was an increase in the thermal stability with increase in the cellulose crystals percentage as depicted by the TGA. The water vapor diffusivity decreased from 7.73 × 10 ⁻⁵ to 2.04 × 10 ⁻⁶ mm ² s ⁻¹ . The improvements in these properties may be attributed to the good interaction between CNC filler and TPS matrix because of similar polysaccharide structures of cellulose and starch.