To understand the thermal stability of the samples, the percent change in the complex viscosity (% ∆η * ) in 20 min of time sweep test was calculated. The box plots in Figure As these reactions lead to a reduction in molecular weight, it's noteworthy that during time sweep tests, which involve a form of thermal treatment, there is a corresponding decrease in complex viscosity . Overall, it appears that pristine HPLA exhibits better thermal stability compared to pristine LPLA. The presence of active sites on the chain ends of PLA causes depolymerization by back-biting (chain end scission or intramolecular transesterification) during high-temperature treatment . Since pristine LPLA has more chain ends due to its lower molecular weight, its lower thermal stability could be attributed to the higher likelihood of depolymerization by back-biting during high-temperature treatment. All of the nanocomposites also exhibited negative % ∆η * , indicating thermal degradation, which was found to be strongly affected by the type of PLA, additive, and composi- The effect of NC on thermal degradation depends greatly on its quantity and the level of dispersion within the polymer matrix. As the degree of NC dispersion increases, its impact on thermal degradation becomes more significant. . Finally, it should be noted that compared to NC-containing counterparts, addition of the GNP in the structure improved the thermal stability of the nanocomposites. This enhancement is attributed to the shielding effect provided by the flake-like structure of GNPs, which effectively hinders the diffusion of volatile decomposition products within the nanocomposites .