Hydrophilic Monomers Graft Gum Arabic Hydrogels Prepared in Different Cross-linking Nature and Study of their Effects on Irrigation of Agriculture Soil

摘要

Gum Arabic (GA) was grafted with acrylic acid (AA), acrylic acid and acrylamide (AAm) mixture, or AA and AAm and N-Vinyl pyrrolidone (VP) mixture. The polymerization process was initiated with ammonium persulphate (APS) and cross-linked, either chemically using N,N`-methylenebisacrylamide (MBA) or physically, where sodium hexameta polyphosphate (SHMP) was used. Degree of swelling (DS) of the prepared superabsorbent polymers were measured in deionized water, river water (around 400 ppm hardness) and in artificial hard water prepared with different concentrations of CaCl2 or MgSO_(4) salt solution. Suitable weight percentage of the hydrogel was mixed with Sandy Soil and studied, for increasing the degree of saturation of Sandy Soil with water, and to extend the time of Sandy Soil water-retention percentage (WR%). Different characterizations of both, starting materials and prepared hydrogels were investigated using different Instrumentals. The FTIR spectroscopy identifications of the important functional groups of both raw materials and prepared hydrogels have shown that grafting of the used monomers on the main polymer chains were occurred. Whereas, XRD technology has shown very intense and sharp peaks, which improve the highly crystalline structure of the hydrogel. Scanning electron microscopy SEM measurements of the hydrogels were provided good quantitative analysis about the elemental compositions and their total percentages in hydrogel, in addition to their morphological images. Thermal analysis including differential scanning calorimetry DSC, and thermogravemetric analysis TGA were studied carefully for both raw materials and their formed hydrogels. In generally an increase in thermal stability were found for produced hydrogels.