Recycling coffee silverskin in sustainable composites based on a poly(butylene adipate-co-terephthalate)/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) matrix

This work investigates the feasibility of using coffee silverskin (CSS), one of the most abundant coffee waste products, as a reinforcing agent in biopolymer based composites. The chemical composition, antioxidant activity and morphology of CSS were studied by specific chemical essays and scanning electron microscopy, whilst the thermal stability and the functional groups available on the surface were investigated by thermogravimetric analysis and infrared spectroscopy, respectively. The thermal stability and fibrous structure of CSS make it suitable as a reinforcing filler in polymer composites, which was confirmed by manufacturing biocomposites with improved stiffness and tensile strength, not degraded by CSS addition when compared to the neat biopolymer.