2.2.3. Fourier transform infrared (FT-IR) analysis
FT-IR spectra of the sample under study were registered with IRFourier spectrometer Nicolet 700 (Thermo Scientific, Madison WI,USA) in the middle range of 400e4000 cm1 IR radiation.
FT-IR spectra were measured using dried samples obtained from
gelatin and modified samples. The following protocol of sample
preparation was used. Hydrogels were maintained at 12 C during 12 h. Then they were frozen at 6 C, unfrozen in dark and centrifuged. The formed sediment dried in a drying cabinet at 50 C for 5 h andfinally at 25C for 20 h. Obtained dryfilms grinded in a ball mill till the state of highly dispersed powder and pressed this powder with KBr forming a pellet which was used for FT-IR spectroscopy measurements.
2.2.4. Microstructure observation
Gel microstructure was examined by the scanning electron
microscopy (SEM) using a microscope S405-A (Hitachi, Tokyo,
Japan) supplied with the SEM LEO-420 software. Gel samples preliminary stored in a desiccator at 12C for 1 day. Before examination, sample of the 333 mm size were frosted (in vacuum) and then metalized with thin (app. 20Å) gold layer under vacuum.