Table 2.

Characteristic IR peaks obtained for the tested materials.

Wavenumber [cm−1]	Assignment	Reference
3000–3600	characteristic of the tensile (valence) bands of the O-H bond	[77,78,79,80,81]
1400 and 1600	characteristic for the asymmetrical and symmetrical tensile vibrations of the carboxylic groups (COO-) and bivalent cross-linking cations
1000–1200	characteristic of the vibrations of the C-O bond
800	characteristic of mannuronic acid
700	characteristic of guluronic acid-binding of crosslinking ions