Chemically and mechanically isolated nanocellulose and their self-assembled structures

► Cellulose nanocrystals and nanofibrils isolated from rice straw yielded up to 20%. ► Isolation by acid hydrolysis, blending and TEMPO oxidation was compared. ► Nanocellulose showed distinctly different sizes and surfaces. ► Nanocellulose had cellulose Iβ crystalline structure with crystallinity up to 91%. ► Nanocellulose self assembled into 153-440 nm fibers upon rapid freezing and drying.