2.3. Characterization
2.3.1. Fourier transform infrared (FTIR) spectroscopy
FTIR spectroscopy (PerkinElmer, GX Model) was used to study changes in the functional groups of gelatin after crosslinking and after reinforcement with CNC. Film forms of CNC, gelatin, gelatin hydrogels, and CNC-gelatin hydrogels were analyzed in the transmittance mode over the range 4000–650 cm−1.