Abstract
Nitrocellulose (NC) is typically synthesized by nitrating cellulose from cotton linter using a mixed acid of H2SO4 and HNO3. Okara, a soybean-processing byproduct often disposed of as waste, contains approximately 40 wt% of insoluble dietary fiber rich in cellulose, making it a promising alternative raw material for NC. In this study, NC was synthesized from okara under different pretreatment and nitration conditions. Light yellow powder (okara NC) was obtained with a maximum crude yield of 18.0%. Elemental analysis and Fourier transform infrared spectroscopy revealed that the chemical structure of okara NC was comparable to that of the reference NC, with a nitrogen content of approximately 12%. When NaOH-pretreated okara was used as the raw material, the resulting product exhibited a structure that more closely resembled that of the reference NC. In this case, thermal analysis indicated a heat amount of 2.20 kJ･g-1 and a decomposition temperature of 143.6°C. Hot water washing after nitration increased the decomposition temperature; however, it remained lower than that of the reference NC.
