Evaluation of thermal degradation and melt crystallization behavior of taro mucilage and its graft copolymer with poly(lactide)

This communication presents the thermal degradation behavior and non-isothermal crystallization kinetics of taro mucilage (CEM) and its graft copolymer polylactide (CEM-g-PLA) by thermogravimetric analysis (TGA/DTG coupled techniques) and differential scanning calorimetric. Isoconversional degradation analysis for CEM and CEM-g-PLA performed with the aid of Friedman, Kissinger (KSS), Flynn–Wall–Ozawa (FWO), and Kissinger–Akahira–Sunose (KAS) methods. The energy profiles and Criado plots over specific conversion (α) were able to predict that both CEM-g-PLA and CEM followed multi step kinetics and different degradation mechanisms. The Ozawa model fitted the melt crystallization data for CEM-g-PLA and its exponent (m) complements those for the modified Avrami and Tobin models. The crystallization of CEM-g-PLA was characterized with the formation of two distinct crystal growths. Further, the negative isoconversional activation energy suggested the occurrence of melt crystallization in CEM-g-PLA. Thus, the grafting of PLA onto CEM resulted into a material that shows thermal properties entirely different from that of its precursor (CEM) besides having an increased shelf life and not compromising with biodegradability. The analyzed data from the isoconversional equations (viz. Friedman, FWO and KAS models) and Ozawa model could be useful in modelling the degradation stability/mechanism and crystallization behavior of polylactide-grafted copolymer.