Sustainable biodegradable coffee grounds filler and its effect on the hydrophobicity, mechanical and thermal properties of biodegradable PBAT composites

Poly(butylene adipate-co-terephthalate) (PBAT) and coffee grounds (CG) wastes are biodegradable materials. The high cost of PBAT restricts its marketability; the lignocellulosic CG were used as a reinforcing agent for PBAT. Thus, the present work focuses mainly on the preparation and characterization of bio-based PBAT composites filled with CG bio-additives with affordable cost, and with potential use in a variety of eco-friendly fields such as packaging, biomedical devices, and composting. The PBAT polymer was melt blended with various contents of CG powder using twin screw extrusion. The compatibility and dispersion state of investigated biocomposites in presence or absence of PEG as plasticizer were investigated by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effect of the addition of PEG on PBAT/CG was characterized by differential scanning calorimetry (DSC), tensile properties, contact angle measurements, and thermogravimetric analysis. The chemical interaction between hydroxyl groups of CG particles and PEG plasticizer was achieved by these techniques. A pyrolysis kinetic model was proposed to identify the kinetic parameters of the thermal degradation of PBAT and CG powder. (c) 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44498.