Utilization of Torrefied Coffee Grounds as Reinforcing Agent To Produce High-Quality Biodegradable PBAT Composites for Food Packaging Applications

The present study has revealed that torrefied coffee grounds (CG) derived from agriculture commodities can be used as bioreinforcing agent for biodegradable poly(butylene adipate- co -terephthalate) (PBAT) without requiring a compatibilizer. The optimum torrefaction operation was achieved in order to increase the hydrophobicity of CG. The raw CG was also used as a reference to assess the effect of the torrefaction operation. The structure and morphology of the composites were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The effect of the addition of raw or torrefied CG on the melting temperature and crystallinity of PBAT biocomposites was analyzed by differential scanning calorimetry (DSC). A significant enhancement in the thermo-mechanical properties for PBAT/torrefied CG composites was observed compared to PBAT/CG composites. Moreover, the hydrophobicity of PBAT composites which was determined by water contact angle was improved when torrefied biomass was added. The thermal stability of the investigated samples was analyzed by thermogravimetric analysis (TGA) and a kinetic model was proposed to describe the thermal degradation of raw CG, torrefied CG, PBAT, and their filled composites. The obtained results for these solvent-free prepared biocomposites show that they can be potential candidates for food packaging applications.