Insights into the production and physicochemical properties of oxycellulose microcrystalline with coexisting crystalline forms

Abstract Oxycellulose microcrystalline (Oxy-MCC) was prepared utilizing nonwood agro-industrial residue, rice husk (RH), via consecutive soda delignification and non-acidic catalytic oxidation. The resultant Oxy-MCC, with a 31 wt% yield, has granular microstructured particles with an average diameter of 41.66 ± 4.11 μm. The porous morphology has been observed in Oxy-MCC micrographs, using scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) and TGA/DTG thermal analysis indicated the presence of typical cellulose characteristics, while the presence of carbonyl spectral peak signalized the efficacy of D-RH oxidation process. The x-ray diffraction (XRD) confirmed the coexistence of cellulosic crystalline forms of cellulose I and cellulose II with 84.8% crystallinity index. Significant growth of crystallite size was observed from 1.7 nm (RH) to 9.4 nm (Oxy-MCC). The maximum decomposition temperature (Tmax) was found to be 324 °C, thus indicating good thermal stability. Oxy-MCC showed, overall, attractive thermal and physicochemical properties for oxycellulose nanocrystalline (Oxy-NCC) production.