Synthesis of phosphoric acid

Poly(lactic acid) (PLA) nanocomposites film reinforced with cellulose nanocrystals (CNCs) extracted from sugarcane bagasse fibre (SBF) was prepared by solvent casting method. The CNCs were obtained through alkaline treatment followed by sulphuric acid hydrolysis or phosphoric acid hydrolysis. The aim of this work was to evaluate the feasibility of utilizing phosphoric acid (mild acid) to extract CNC from the SBF. The properties of the CNC were investigated by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The thermal properties of the PLA/CNC nanocomposites were characterized using thermogravimetric analyser (TGA). TEM results demonstrated that the CNC having diameter of 5.5–6.2 nm and length of 235–300 nm. Results from XPS characterization have confirmed the existence of both sulphate group and phosphate group in the H2SO4-treated CNC (S-CNC) and H3PO4-treated CNC (P-CNC). FTIR results indicated that the presence of hydrogen bonding and chemical interaction between PLA and CNC. The thermal stability of PLA/P-CNC-10 is higher than that of PLA/S-CNC-10 nanocomposites attributed to the char formation of P-CNC in the PLA matrix