Non-isothermal degradation kinetics of PLA-functionalized gum (fG) biocomposite with dicumyl peroxide (DCP)

Abstract

The effect of functionalized gum arabic (fG) on the thermal decomposition behaviour of poly(lactic acid) (PLA) in the presence of dicumyl peroxide (DCP) is investigated from the thermogravimetric analysis (TG) and coupled TG–Fourier transform infrared spectroscopy (FTIR) techniques. A series of fG-grafted PLA film in the presence of DCP are facilely fabricated using reactive extrusion at a set processing parameters, i.e. temperature and speed of screw are maintained at 180 °C and 60 rpm, respectively. As compared to PLA, thermal stability is reduced with the increase in the fG content. The addition of DCP could assist to maintain the thermal stability of PLA-1fG-based biocomposites. The activation energy (Ea) is evaluated using the model-free approach, i.e. (1) modified Coats–Redfern (CR), (2) Flynn Wall Ozawa (FWO) and (3) Kissinger method rely on a set of dynamical TG experiments. The value of Ea determined using Kissinger method is 158 (PLA), 143 (PLA-1fG), 125 (PLA-3fG), 154 (PLA-D-1fG) and 140 kJ mol−1 (PLA-D-3fG), respectively. Generalized kinetic plots suggest that mechanism change A2 (2D nucleation and growth) to R3 (3D phase boundary controlled reaction) for PLA, PLA-1fG, shift A2–A4 (4D nucleation and growth) for PLA-3fG and A2–R2 (2D phase boundary controlled reaction) in case of DCP-treated PLA-fG biocomposites. The releases of decomposed products for gum arabic, fG, PLA-fG-based reactive biocomposite are investigated using TG–FTIR technique.