Synthesis of poly(acrylamide-co-acrylic acid)-based super-absorbent hydrogels by gamma radiation: study of swelling behaviour and network parameters

A series of poly(acrylamide-co-acrylic acid) (poly(AAm-co-AAc))-based super-absorbent hydrogels (SAHs) was prepared by gamma radiation at the dose rate of 15 kGy. The amount of AAm was varied in the range of 30-70% (mol of total monomer) in feed. The co-polymers were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, nuclear magnetic resonance and network parameters, such as average molar mass between cross-links and cross-link density, were determined to explain the swelling behaviour. The experimental results indicated that an increase in the AAm content present in the hydrogels varied from 38.87% to 64.02%, equilibrium water absorbency decreased from 872 to 402 g H2O/g sample. The equilibrium water absorbency of various SAHs was investigated in different concentration of saline solutions. The effect of synthesized co-polymer on growth of seeds of ladyfinger is reported.