Synthesis And Characterization of Cellulose-Poly (Acrylamide-Co-Acrylic Acid) Graft Copolymer Hydrogel from Rice Straw

Abstract

In this work, cellulose-poly(acrylamide-co-acrylic acid) graft copolymer hydrogels were prepared by free radical copolymerization of acrylamide and acrylic acid onto cellulose that had been extracted from rice straw, using Potassium persulphate as initiator and N,N’-methylenebisacrylamide as crosslinker. The extracted cellulose and synthesized graft copolymer hydrogel were characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive x-ray spectroscopy (EDX) and Differential scanning calorimetry (DSC). The FT-IR spectrum of the graft copolymer shows a band at 1048cm^-1 which correspond to C-O-C linkage confirming the successful grafting of the polymer on to the cellulose fibre. The diffraction pattern of raw rice straw obtained from XRD has an amorphous pattern and extracted cellulose obtained from XRD shows that, it has an amorphous pattern in raw rice straw and the extracted cellulose has a crystalline pattern. Morphologies of raw rice straw, extracted cellulose and that of synthesized hydrogel obtained shows that, the raw rice straw has a rough surface, the extracted cellulose has a smooth surface, and the hydrogel has a triangular shape with smooth surface. The glass transition temperature (Tg) and the melting temperature (Tm) of the hydrogel were found to be 31.43^oC and 92.44^oC respectively. (EDX) analysis shows a decrease in weight concentration of Silicon from 77.59 to 23.90, while that of Carbon increased from 22.41 to 57.03 after bleaching treatments. The hydrogel shows high water absorbency of 1141.28% at pH = 7. The synthesized hydrogel has the potential to be applied in waste water treatment, metal-ion removal, drug carrier and other fields where effective water utilization is essential.