Valorization of Coffee Husk in Ternary Bio-Composites: Synergistic Reinforcement of Bio-Epoxy/Polylactic Acid for Enhanced Mechanical and Physical Properties

This study investigated Coffee arabica husk (CAH) as a reinforcing filler to create sustainable biocomposites from agro-industrial waste. The research explored the relationship between processing, structure, and properties using two matrices: polylactic acid (LA) and a bio-based epoxy resin (BER). We found that CAH incorporation increased the elastic modulus in all composites, with the stiffening effect being more significant in BER-based systems. However, filler inclusion dramatically reduced composite toughness. Our analysis showed that melt processing significantly reduced the CAH aspect ratio, with BER causing a more pronounced reduction than LA. Conversely, LA showed a greater tendency to fill the porous voids of the CAH particles. This work demonstrates the crucial interaction of filler, matrix, and processing on a composite’s final performance. These materials have shown promises for sustainable packaging and other technical applications.