Thermal and rheological properties of gelatin-dextran hydrogels

Hydrogels prepared by crosslinkage of gelatin with dextran dialdehyde have been characterized by dynamic shear oscillation measurements at small strain. Isothermal as well as temperature scan measurements were performed. The results obtained demonstrated that the final polymer network is a result of a chemical gelatin-dextran dialdehyde interaction as well as a gelatin-gelatin (physical association) and a polymer-solvent interaction. This balance is strongly dependent on the composition of the system, the polymer concentration, the storage temperature and the storage time.We found that a short cryogenic treatment at –20°C of physically structured gels, significantly increases the chemical crosslinkage. DSC measurements at low cooling rate confirm these results and demonstrate a chemical reaction enthalpy contribution.This work was supported by the Flemish Institute for Science and Technology (IWT) and the Belgian Government (PAI-III-40).The authors also express their gratitude to Systèmes Bio Industries Benelux for providing free samples of well characterized gelatin.