Spent coffee waste as a renewable source for the production of sustainable poly(butylene succinate) biocomposites from a circular economy perspective

Turning waste products into useable resources is a necessity for the sustainable future of our planet. Such is the case with popular beverage coffee that produces solid waste in the form of spent coffee grounds (SCG). There is an opportunity to use SCG material as a cheap, sustainable, and biodegradable polymer filler that is received as waste from espresso machines. There have been relatively many studies that prove the concept of various agricultural and forestry waste, which can be integrated into modern green materials. Building upon this concept, we have selected a promising polyester poly(butylene succinate) (PBS) as a matrix owing to its bio-based and biodegradable nature. High loadings of SCG from 20 to 60 wt% were tested for optimal composition performance. Tensile, dynamic mechanical, thermal, and structural properties of the composites were examined, while their biodegradation in composting conditions was also analyzed. SCG filler showed different performance from various cellulose fiber-based composites, and properties significantly varied depending on loading. Compared to neat PBS, biodegradation occurred twice as fast for composite materials with high SGC loadings.