Interpenetrating network formation in gellan-agarose gel composites

Thermal, mechanical, turbidity, and microscope evidence is provided which s trongly suggests molecular interpenetrating network (IPN) formation by mixt ures of the bacterial and seaweed polysaccharides gellan and agarose. There is no evidence for synergistic coupling of the networks, and simple phase separation (demixing) can definitely be ruled out. Some changes in the gell an gelling behavior are suggested, however, by the increased gellan effecti ve concentrations implicit in cure curve data. The dependence of this effec t on the agarose nominal concentration seems consistent with a previous mod el that focused on gelling parameters, and changes in these, rather than re al concentration effects. In large deformation mechanical tests, the influe nce of agarose added to gellan is to re-enforce the network (higher compres sion and shear moduli, higher stresses-to-break) without significantly chan ging the strain to break, or the gellan brittle failure mechanism.