Synthesis, Characterization and Swelling Behaviour of Guar Gum-g-poly (Methyl Methacrylate) Superabsorbent Nanocomposite

In this work, polymer nanocomposite was synthesized based on guar gum (GG) and methyl methacrylate (MMA) by free radical graft copolymerization reaction using boric acid as a cross linking agent and hydrogen peroxide as an initiator in complete aqueous solution to make it environmental friendly. The composite was synthesized to be used as superabsorbent for the purpose of water absorption. Fourier transform infrared (FTIR) analysis was carried out to confirm grafting of methyl methacrylate onto guar gum. The morphological study of composite was carried out by scanning electron microscopy (SEM). Thermal gravimetric analysis (TGA) confirms the stability of nanocomposite. The composite was characterized by X-ray diffraction (XRD) to study its crystalline nature. The water absorption capacity of superabsorbent was measured in distilled water by free swelling method as a function of percentage swelling and found to be 3000%. The effect of reaction parameters such as guar gum concentration, monomer concentration, initiator concentration, cross-linker concentration and temperature was investigated. The percentage swelling of superabsorbent composite was studied at various pH values between 2.0 and 13.0. The swelling behaviour of composite was also examined in saline solutions. Result shows that swelling capacity is decreased by increasing the ionic strength of swelling medium. This behavior is because of charge screening effect for monovalent cations as well as ionic crosslinking for multivalent cations.