Physicochemical and biodegradation properties of flexible poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide)/spent coffee grounds biocomposites

This study is aimed to prepare and characterize the poly(L-lactide)- b -poly(ethylene glycol)- b -poly(L-lactide)/spent coffee grounds (PLA-PEG-PLA/SCG) biocomposites compared to PLA/SCG biocomposites. The biocomposites were prepared by melt mixing. Fourier transform infrared (FTIR) spectroscopy shows that the PLA-PEG-PLA matrix chemically interacted with SCG but the PLA did not interact. Scanning electron microscopy (SEM) of the biocomposite fractured surfaces indicates that the phase compatibility between PLA-PEG-PLA matrix and SCG dispersed phases was better than between the PLA matrix and SCG dispersed phases. The addition of SCG decreased crystallizability of both the PLA-PEG-PLA and PLA matrices as determined by differential scanning calorimetry (DSC). The thermal stability of PLA fraction in the PLA-PEG-PLA/SCG biocomposites studied from thermo-gravimetric analysis (TGA) largely increased with an increase in the SCG content but this decreased in the PLA/SCG biocomposites. The hydrophilicity of the biocomposite surfaces and water uptake increased by the addition of SCG for both the composite types. Both the PLA/SCG and PLA-PEG-PLA/SCG biocomposites showed lower mechanical properties compared to their pure polymers. However, the PLA-PEG-PLA/SCG biocomposites were still higher flexible than the PLA/SCG biocomposites. The incorporated SCG accelerated the biodegradation in burial soil of both the biocomposite types. The results have shown that PLA-PEG-PLA/SCG biocomposites could be used as a flexible and biodegradable packaging.