ACETYLATION OF LINSEED HYDROGEL: SYNTHESIS, CHARACTERIZATION, ISOCONVERSIONAL THERMAL ANALYSIS AND DEGRADATION KINETICS

Abstract

Linseed (Linum usitatissimum L.) hydrogel (LSH), consisting of polysaccharide rhamnogalacturonans, was acetylated using acetic anhydride and 4-dimethylaminopyridine (DMAP). Acetylated LSH (ALSH) was thoroughly characterized using different spectroscopic techniques. A moderate to high degree of substitution (2.11-2.91) of acetyl groups on LSH was obtained, as calculated by the acid-base titration method. Isoconversional thermal analysis and degradation kinetics of LSH and ALSH were studied. The TG curves of LSH and ALSH exhibited two- and one-step exothermic degradation, respectively. The energy of activation (E-a) values were calculated by the Kissinger and FWO models for the first step of degradation of LSH and ALSH, and were found in the range of 118.32 and 169.18 kJ mol(-1), respectively. The comprehensive index of thermal stability (ITS) was found to be 0.41 and 0.49 for LSH and ALSH, respectively. Thermal data showed that thermal stability was imparted to LSH after acetylation.