Effect of Surface Modification of Coffee Grounds on Epoxy Composites

Spent coffee grounds (SCG) are one of the most common waste products contributing to environmental problems, with their volume continuously increasing. The most efficient way to utilize SCG is by leveraging their large amounts of organic matter and oils for energy production. This study investigates the recycling potential of cellulosic structures after the removal of organic matter and oils. Surface changes in the organic matter of SCG were examined as a function of washing time using FE-SEM, FT-IR, and XRD. As washing time increased, significant changes in particle size were observed, and the tensile properties were evaluated at varying concentrations to assess their suitability as a reinforcing material in epoxy composites. The study found that the reinforcement effect of SCG was minimal under conditions of high polymer crystallinity, indicating that a minimal organic layer is necessary to promote interfacial adhesion between SCG and epoxy. Ultimately, it was determined that SCG is best used in epoxy composites at concentrations of 1 wt% or less. This research provides a potential method for recycling various types of coffee grounds.