Fig. 2. (A) Infrared spectra of amine-modified CNC. CNC-COOH (red line), CNC-TRIS (green line), CNC-EDA (blue line) and CNC-PEI (black line). Successful oxidation is indicated by C O carbonyl stretching at 1712 cm⁻¹ as seen in CNC-COOH, and amine modification is indicated by emergence of N–H bending modes at 1585 cm⁻¹. (B) TGA analysis of CNC (pink line), CNC-COOH (red line), CNC-TRIS (green line), CNC-EDA (blue line) and CNC-PEI (black line).