Effects of amylose/amylopectin starch on starch‐based superabsorbent polymers prepared by γ‐radiation

Abstract

Biodegradable superabsorbent polymers (SAPs) were synthesized in this study by graft copolymerization of acrylic acid onto amylose and amylopectin using N,N ′‐methylenebisacrylamide as a cross‐linker, initiated by an initiator (potassium persulfate) and γ‐ray radiation, respectively. The structures of the resultant amylose‐ graft ‐poly(acrylic acid) (amylose‐g‐PAA) and amylopectin‐ graft ‐poly(acrylic acid) (amylopectin‐g‐PAA) SAPs were characterized by Fourier transform infrared (FTIR) spectroscopy, solid‐state 13 C nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetric analysis (TGA). The main purpose of this study is to investigate the effects of the two initiation modes and chain structures of starches on the grafting ratios (GR) and properties of these amylose‐g‐PAA and amylopectin‐g‐PAA SAPs. The results show that SAPs prepared by γ‐radiation have higher water absorption and GR than SAPs prepared by the initiator. In addition, amylose‐g‐PAA SAPs have higher water absorption and GR than amylopectin‐g‐PAA SAPs. The optimum water absorption is 530 g/g for amylose‐g‐PAA SAPs and 355 g/g for amylopectin‐g‐PAA SAPs, respectively. It is concluded that γ‐radiation is more time‐saving, energy‐saving, and efficient than the initiator.