Preparation of a starch-based superabsorbent polymer by γ-ray irradiation and investigation of its properties

A super absorbent polymer (SAP) was prepared using starch and acrylic acid under exposure to 60Co γ-rays irradiation. The chemical structure of the SAP was characterized by Fourier-transform infrared spectroscopy Scanning electron micrographs showed that the surface of the SAP contained numerous mesoporous structures. Thermogravimetric analysis indicated improved thermal stability of the SAP compared to that of the original starch. The absorbed dose and feed ratio of the acrylic acid and starch significantly affected the water absorption performance of the SAP. The water absorption capacity of the SAP was 532 g/g at the optimal conditions (absorbed dose: 20 kGy, crosslinking agent: 80 mg/L, feed ratio of starch to acrylic acid: 1/2). The SAP efficiently released the loaded KNO3 or Na3PO4; the release rates were 82% for K+ and 80% for PO43-.