A MIXED SYSTEM COMPOSED OF DIFFERENT MOLECULAR-WEIGHTS KONJAC GLUCOMANNAN AND KAPPA-CARRAGEENAN - LARGE-DEFORMATION AND DYNAMIC VISCOELASTIC STUDY

Rheological properties of mixed gels of konjac glucomannan (KGM) of four different molecular weights with kappa-carrageenan (CAR) were studied by dynamic viscoelastic measurements and tensile testing. Both storage and loss moduli for sol and gel state mixtures containing higher molecular weight KGM were highest. However variation in molecular weight of KGM produced little effect on the gel-to-sol and sol-to-gel transition temperatures of the mixtures. Two systems containing KGM of lower molecular weights showed almost the same stress-strain curves in tensile testing. The breaking stress and the breaking strain for mixed gels became larger with increasing molecular weight of KGM, and the difference was larger than that observed in the dynamic viscoelasticity measurements. It was suggested that weak junction zones are created by the addition of KGM and that the number of weak junction zones and the contour length of flexible chains connecting these weak junction zones increase with increasing molecular weight of KGM.