This work reports the findings on the water absorption
properties of hydrogels based on the cross-linked carboxymethyl
starch using di- or polyfunctional carboxylic acids
as the cross-linkers. The results show that: (1) Hydrogels
were formed based on the network established from the
cross-linking of the starch molecules. (2) The absorption
under load (AUL) and the free swelling capacity (FSC)
which are the technical parameters showed that the
hydrogels are sensitive to both the salinity and the pH of the absorbed medium, thus providing relevant information
for the possibility of physiological applications (3) The
polyfunctional carboxylic acid did not provide effective
cross-linking compared with the difunctional carboxylic
acids among which there are no remarkable differences
in the rheological parameters investigated. The strength
of the investigation is that cheap, readily available and
renewable resources are used to produce novel hydrogels
which could be used for diverse technical applications, particularly
where moderate swelling/water absorption is
required.