Drying and shrinkage of polymer gels

Abstract

The polymer hydrogel was synthesized by photo-polymerization process (UV light, 60°C) in presence of Photo-initiator (IrgacureR) and Cross-linker (NN'-methylene bisacrylamide; MB AM). 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.