Development of Sustainable <scp>PHBV</scp> Biocomposites Reinforced With Spent Coffee Ground Waste for Packaging Applications

ABSTRACT The valorization of agro‐industrial waste such as spent coffee grounds (SCG) offers a sustainable strategy for developing biodegradable materials. This study explores the incorporation of SCG as a biofiller in poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) biocomposites. The effects of SCG particle size (fine vs. coarse) and filler loading (1–7 wt.%) on mechanical, thermal, surface, and biodegradation properties were systematically examined. Biocomposites with fine SCG at 5 wt.% showed the best overall performance, achieving a 16% increase in tensile strength (32.9 MPa) and a 23% rise in flexural strength (31.7 MPa) compared to neat PHBV. Coarse SCG fillers enhanced thermal stability, with a peak degradation temperature of 290°C at 3 wt.% loading. However, higher filler contents caused agglomeration and weakened interfacial bonding. Coarse SCG composites also exhibited greater water absorption (0.76%) and biodegradation (17.9% mass loss after 60 days) due to increased porosity. Two‐way ANOVA with Tukey's test ( p &lt; 0.001) confirmed that both particle size and filler loading significantly affected mechanical performance. These findings demonstrate the potential of SCG as a low‐cost, circular biofiller and highlight particle size optimization as a key factor in engineering PHBV‐based biocomposites for eco‐friendly packaging applications.