RATIONALIZATION OF THE ELASTIC-MODULUS MOLECULAR-WEIGHT RELATIONSHIP FOR KAPPA-CARRAGEENAN GELS USING CASCADE THEORY

Literature results for the variation of the elastic modulus of kappa-carrageenan gels with molecular weight have been modelled using cascade theory. Excellent fits have been obtained. The critical nature of gelation is used to explain inhibition of gelation below a lower molecular weight threshold, while constancy of modulus at higher molecular weights is attributed to optimum effectiveness of the cross-linking process. Such behaviour can be anticipated both for reversible and irreversible cross-linking mechanisms, but is crucially dependent on there being proportionality between molecular weight and the number of sites for crosslinking per molecule. Parameters of the model, determined by least-squares fitting, are discussed in the light of recent developments in the cascade theory description of biopolymer gelation.