Abstract

WAJE, S. S. et al. Drying and shrinkage of polymer gels. Braz. J. Chem. Eng. [online]. 2005, vol.22, n.2, pp.209-216. ISSN 0104-6632.  http://dx.doi.org/10.1590/S0104-66322005000200007.

The polymer hydrogel was synthesized by photo-polymerization process (UV light, 60 ºC) in presence of Photo-initiator (Irgacure^R) and Cross-linker (NN'-methylene bisacrylamide; MBAM). In the present work, the drying of polymer hydrogel was carried out to study the effect of temperature, gel-sheet thickness, monomer ratio of acryl acid to acrylamide (AA/AM), concentration of MBAM and quantity of monomers. A correlation has been developed for modified sheet thickness as a function of contraction coefficient and degree of drying. Effective diffusivity was estimated from Fickian-diffusive model considering modified sheet thickness and was found to be in the range of 1.1 ´ 10^-10-5.93 ´ 10^-10 m²/s. The activation energy obtained using Arrhenius type equation was found to be in the range of 2979-10737 kJ/kmol H₂O. The drying behavior shows an initial shoot-up in drying rate followed by constant rate and two falling rate periods.

Keywords : Polymer gel; Drying characteristics; Diffusion coefficient; Modified gel thickness; Contraction coefficient.

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