Comparative Isoconversional Thermal Analysis and Degradation Kinetics of Acetylated Mimosa Pudica (Touch-Me-Not) Hydrogel

Comparative thermal degradation and kinetics of hydrogel of Mimosa pudica (MPH) and acetylated Mimosa pudica hydrogel (AMPH) were investigated. Thermogravimetric (TG) analyses of MPH and AMPH was carried out and analyzed using isoconversional method. Kinetic parameters such as energy of activation (Ea) were calculated by fitting the thermal data to Flynn Wall Ozawa (FWO) and Kissinger methods. The order of thermal degradation reactions (n) was evaluated using Kissinger method. TG curves of both MPH and AMPH exhibited two step exothermic degradation. The Ea values calculated by Kissinger and FWO models for first step of degradation of AMPH were found in the range of 105.41-108.49 and 153.67-163.77 kJ mol-1 for the second step which were comparable with the Ea values of the unmodified MPH. The mean values of integral procedural decomposition temperature (IPDT) for MPH and AMPH were found to be 338 degree C and 346 degree C, respectively. The mean comprehensive index of thermal stability (ITS) was found to be 0.55 for MPH and AMPH showing both materials much stable than many commercially available ingredients used in drug designing. (author)