Bioplastic based on starch and cellulose nanocrystals from rice straw

Bioplastic based on starch as the matrix and cellulose nanocrystals from rice straw as reinforcing filler were prepared in this study. The isolation of cellulose nanocrystal (CNC) followed a series of steps: delignification, sulfuric acid hydrolysis, and sonication. The process afforded short, rod-like CNCs with particle diameter ranging from 10 to 12 nm and crystallinity index of 76.1%. Fourier transform infrared analysis of the CNCs also confirmed absorption patterns typical of cellulose and the removal of silica. Bioplastic with different starch-to-CNC ratios were prepared by solution casting and evaporation method. Scanning electron micrographs of the films showed uniform dispersion of CNC in the starch matrix. Mechanical tests revealed that both tensile strength and modulus significantly increased with increasing CNC load while percent elongation decreased. The moisture uptake of the films reinforced with CNC also decreased an indication of improvement in water resistance. However, the thermal stability of the films decreased by the addition of CNC.