Speaker
Description
This study aims to enhance the properties of sodium alginate by grafting phosphate and nitrogen onto its structure. A novel and sustainable esterification reaction involving sodium alginate, phosphoric acid, and urea was developed. The modified material, which is water-soluble but insoluble in various organic solvents, was characterized using a range of analytical techniques, including Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDX), Nuclear Magnetic Resonance (NMR), Thermogravimetric Analysis (TGA), and potentiometric titration. The results confirm the presence of phosphate groups on the polysaccharide chains, with a significant proportion containing nitrogen. The degrees of substitution (DS) for phosphate (4.13) and nitrogen (3.25) indicate that hydroxyl groups are modified with phosphate groups (both mono- and di-phosphates) containing nitrogen in the form of -CO-NH2. Potentiometric titration reveals two broad buffer zones, indicating the presence of various acidic groups (-COOH) along the alginate chains. A flammability test demonstrates that the modified material exhibits flame-retardant properties, significantly reducing combustion rate and enhancing thermal stability. These findings highlight its potential application in materials requiring high fire resistance.
