Interpenetrated network formation from poly (vinyl alcohol)/sodium polyalginate aqueous solutions and the rheological properties

Gelation behaviors of poly (vinyl alcohol)/sodium polyalginate (PVA/ALG) aqueous solutions with low ALG content (PVA: 21 g/dL; ALG: 0.55 g/dL) were examined by dynamic mechanical analysis and small angle neutron scattering (SANS). The gelation process does not depend on the order of the gelation of components; SANS intensities at small wave vectors q as well as at high q are almost equal to the sum of the values for the components. Young's moduli E and E_PVA for PVA/ALG gel films immersed in CaCl₂ solutions and PVA film immersed in water, respectively, were obtained by simple elongation measurements. The increment of modulus ΔE = E - E_PVA, was proportional to the CaCl₂ concentration. From these results, we concluded that PVA/ALG systems with low ALG content compose an interpenetrating network and that the final structure does not depend on the gelation order of components.