Drying of polyacrylamide composite gels formed with various kappa- carrageenan content

Drying of polyacrylamide (PAAm)-κ-carrageenan (κC) composite gels were monitored by using steady-state fluorescence technique. Disc shaped gels were formed from acrylamide (AAm) and N, N'- methylenebisacrylamide(Bis) with various κ- carrageenan (κC) contents by free radical crosslinking copolymerization in water. Pyranine (P) was doped as a fluorescence probe, and scattered light, I (sc), and fluorescence intensities, I, were monitored during drying of these gels. It is observed that fluorescence intensity of pyranine increased as drying time is increased for all samples. The increase in I was modeled using Stern- Volmer equation and diffusion with moving boundary. It is found that desorption coefficient, D decreased as κC contents were increased. Supporting gravimetrical and volumetric experiments were also carried out during drying of PAAm- κC composite gels.