Swelling Properties and Kinetics of Starch-g-Poly(acrylic acid) Hydrogels

Starch-g-poly(acrylic acid) (CSt-g-PAA) hydrogels were prepared from cassava starch and acrylic acid by graft polymerization. The hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric-differential scanning calorimetry (TG-DSC). Additionally, the water absorbency and hygroscopic swelling properties of the hydrogels were investigated respectively. The two processes were simulated using mathematical modes. The results revealed that the crystal structure of starch was destroyed. At 40°C and relative humidity 90% (90% RH), the samples (starch mass15%, 50%) have a better performance of the moisture absorption. Hygroscopic rate declined with the increase of relative humidity.