Synthesis and characterisation of starch grafted superabsorbent via 10 MeV electron-beam irradiation

A starch-graft-polyacrylamide (St-g-PAM) superabsorbent crosslinked by N,N′-methyl bisacrylamide (MBA) was prepared using 10 MeV simultaneous electron beam irradiation at room temperature and subsequent alkaline hydrolysis. The effects of the irradiation dose, acryliamide-to-anhydroglucose unit (AM-to-AGU) ratio and crosslinker amount on the properties of the obtained polymers were evaluated. The structure of the graft copolymer was confirmed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). Optimisation treatments were carried out and found for a total dose of 8 kGy, an AM-to-AGU ratio of 4.5 mol mol−1 and a crosslinker-to-AM ratio of 0.4% mol mol−1. The obtained superabsorbent polymer showed the maximum absorptions of 1452 g g−1 and 83 g g−1 for distilled water and saline solution, respectively (relative to its own dry weight). The results suggest 10 MeV electron beam irradiation is more efficient than γ-ray irradiation due to its higher energy and dose rate.