Rheologica Acta, Vol.59, No.11, 765-770, 2020
Effect of moisture in kappa-carrageenan films on their tensile and relaxation behavior studied by correlation between stress and birefringence
A picture on the molecular level describing the deformation and the following relaxation of kappa-carrageenan chains has been proposed based on the three-domain structural model for kappa-carrageenan films and on the idea of the modified stress-optical rule. The uniaxial tensile and the relaxation behavior for dry and moist kappa-carrageenan films has been examined by using a homemade apparatus available for the simultaneous mechanical and birefringence measurements. It has been suggested that the continuous amorphous phase of kappa-carrageenan in the dry film is deformed together with the local glass component, and only the glass component relaxes in the following process. On the other hand, concerning the moist film, the crosslinks of kappa-carrageenan aggregates in addition to the continuous phase are movable with deformation, while the following relaxation is attributed only to the unbridged kappa-carrageenan chains in the continuous phase.