Temperature effect on the swelling of PAAm‐κ‐carrageenan composites

Abstract

AbstractThe steady‐state fluorescence (SSF) technique was used for studying swelling of disc‐shaped polyacrylamide (PAAm)‐κ‐carrageenan (κC) composites which were prepared by free‐radical crosslinking copolymerization at 80°C. Pyranine was introduced as a fluorescence probe during polymerization. Swelling experiments were performed in water at various temperatures by real‐time monitoring of the pyranine (Py) fluorescence intensity, I which decreased as swelling proceeded. Stern–Volmer equation is modified for low quenching efficiencies to interpret the behavior of Py intensity during the swelling of PAAm‐κC composites. The Li‐Tanaka equation was used to determine the swelling time constants, τ1, and cooperative diffusion coefficients, D0, from fluorescence intensity, weight, and volume variations of the composites at various temperatures. It was observed that τ1 first decreased up to 40°C and then increased; naturally, D0 increased up to 40°C and then decrease for all κC content gels. Swelling activation energies, ΔE, were measured for the swelling composites, which are found to be exothermic and endothermic in between 30–40 and 40–60°C, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012