Effect of Hydrolysis Time on Nanocrystalline Cellulose From Bogor‐Variety Sago Waste

ABSTRACT Sago bagasse, an abundant lignocellulosic by‐product with potential as a renewable source of nanocrystalline cellulose (NCC). This study aims to evaluate the effect of hydrolysis time (60 and 75 min) on the physicochemical properties of NCC prepared from Bogor‐variety sago waste, followed by ball milling as a post‐treatment for powder homogenization. NCC was characterized using particle size analysis, x‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), field‐emission scanning electron microscopy (FE‐SEM), and energy‐dispersive x‐ray spectroscopy (EDS). Based on dry sago bagasse, the overall NCC yield decreased from 14.85% at 60 min to 0.93% at 75 min. NCC75 showed a smaller particle size (32.1 nm) and lower polydispersity index (0.223) than NCC60 (85.9 nm; 0.447), while NCC60 exhibited slightly higher crystallinity (86.80%) than NCC75 (85.40%). Thermal behavior NCC75 exhibited a higher enthalpy change (ΔH: 936.54 J/g) and a higher endothermic peak temperature at 54.45°C compared to NCC60 (ΔH: 399.45 J/g) and an endothermic peak at 44.07°C. The prolonged hydrolysis leads to more pronounced low‐temperature thermal transitions and indications of increased structural disorder, indicating decreased thermal resistance despite higher enthalpy values. The EDS also detected Na‐ and S‐containing residues, suggesting sulfate‐related surface modification and/or residual neutralization salts. The hydrolysis process at 60 min achieved a balance among yield, crystallinity, and thermal stability. These findings may serve as a guide for the future optimization of the NCC synthesis process.