Environmental Impacts of Graphene Oxide for Enhancing Crystallization Behavior and Promoting Degradation of Polylactic Acid in Saline Solution

The influence of the graphene oxide (GO) in weight percentage from 0.05 to 0.6 wt % on the PLA's physical properties was investigated using X-ray Diffraction (XRD), DSC, thermogravimetric analysis, polarized optical microscopy, and impedance measurements. The experimental results indicate that incorporating GO into Polylactic acid (PLA) improves its thermal properties by quickly reaching the optimum percentage of crystallinity (from ∼8.5 to 55%), slightly increasing the maximum thermal degradation temperature (from 340 to 347 °C), and drastically reducing the size of PLA's spherulites. Additionally, the electrical impedance values decreased by 64% as the percentage of GO increased from 0.05 to 0.6 wt %. Furthermore, the PLA composite was soaked in a 10 wt % NaCl solution for different time intervals of up to 21 days. The electrochemical behavior of the PLA-GO composite was investigated by using electrochemical impedance spectroscopy. The electrical conductivity change was performed as a function of the charge-transfer resistance. For the PLA-GO-0.6 sample, the charge-transfer resistance increased by approximately 26% after 21 days of immersion in NaCl solution, attributed to the swelling of graphene oxide (GO). Optical microscopy revealed notable changes in surface morphology during soaking in 10 wt % NaCl, with the formation of irregular channels resulting from the expansion of GO within the PLA matrix.