Synthesis and characterization of starch‐g‐Poly(acrylic acid)/Organo‐Zeolite 4A superabsorbent composites with respect to their water‐holding capacities and nutrient‐release behavior

Novel superabsorbent composites were prepared using starch, acrylic acid, and organo‐zeolite 4A micropowder via aqueous solution graft copolymerization. The effects of organo‐zeolite 4A content on water absorbency were tested to determine the optimum conditions that ensure a high swelling ability. Under these conditions, the maximum swelling ability in distilled water was determined to be 511 g/g when the amount of organo‐zeolite 4A in the feed was 10 wt%. The prepared samples were characterized with Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscope (SEM). The SEM characterization of the samples indicated that the superabsorbent composites had more pores and water than zeolite‐free superabsorbents. The swelling capacities in distilled water, various salt solutions, and aqueous urea were studied. The on–off switching behavior and the release of urea from the loaded starch‐g‐ poly(acrylic acid)/organo‐zeolite 4A were also determined. The results indicated that the novel composite was responsive to salts and exhibited on–off switching behavior, as evidenced by reversible swelling and de‐swelling. In addition, the slow nutrient release makes this material suitable for many potential applications in the fields of agriculture and horticulture. POLYM. COMPOS., 38:1838–1848, 2017. © 2015 Society of Plastics Engineers