Acetylation Modification of Rice Straw Fiber and Its Thermal Properties

The esterification of rice straw fiber with acetic anhydride, using sulphuric acid as catalyst, under mild conditions in glacial acetic acid, has been investigated. Acetylation conditions, such as dosage of chemicals and catalyst, and time and temperature of acetylation, were optimized. The preferred reaction parameters of acetylation reaction are described as follows: weight ratio of rice straw and acetic anhydride was 1:3, using sulphuric acid as catalyst in glacial acetic acid at 50 °C for 2 h, the dosage of catalyst and solvent was, respectively, 9.0% and 9 times to rice straw powder, in which the acetylation weight percent gain of 40.1% was obtained. The characterization of acetylated rice straw was performed by Fourier transform infrared (FTIR), Nuclear Magnetic Resonance (H NMR), X-ray diffractometer (XRD), Scanning electron microscope (SEM). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed a slow decomposition rate, compared to raw rice straw, and an endothermic peak at 188 °C. These results demonstrated that the thermal properties of rice straw can be improved by acetylation.