Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE A hybrid PLA/TPS biocomposite reinforced with spent coffee grounds and compatibilized with maleic anhydride shows improved interfacial adhesion, balanced melt processability, and enhanced functional performance. The optimized AK 10% + MA formulation achieves 29.86 MPa tensile strength, low water absorption, and 28.03% biodegradation after 3 months, highlighting waste-derived fillers for sustainable bioplastics.

ABSTRACT
This study developed hybrid poly(lactic acid) (PLA)/thermoplastic starch (TPS) biocomposites reinforced with spent coffee grounds (AK, 0–30 wt%) and compatibilized with maleic anhydride (MA, 5 wt%). The composites were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), tensile testing, melt flow rate (MFR), water absorption, and soil-burial biodegradability. Increasing AK content improved stiffness and biodegradation because of its lignocellulosic structure; however, excessive filler loading caused agglomeration and reduced ductility. MA enhanced interfacial compatibility, filler dispersion, stress transfer, and moisture resistance at low to moderate AK contents. The AK 10% + MA formulation showed the most balanced performance, achieving a tensile strength of 29.86 MPa, low water absorption, favorable melt flow behavior, and 28.03% weight loss after 3 months of soil burial. These results clarify the role of AK and MA in controlling the processing–structure–property–biodegradation relationship of PLA/TPS composites and support the use of spent coffee grounds as sustainable fillers for biodegradable bioplastics.