No Such Thing as Trash: A 3D-Printable Polymer Composite Composed of Oil-Extracted Spent Coffee Grounds and Polylactic Acid with Enhanced Impact Toughness

Primary Author: Yu-Chung Chang

Faculty Sponsor: Yuehe Lin


Primary College/Unit: Voiland College of Engineering and Architecture

Category: Engineering and Environmental Science

Campus: Pullman




Principal topic: As one of the most popular beverages in the world, a large amount of coffee wastes known as the spent coffee grounds (SCGs) is generated daily. It would be a waste if these SCGs is directly dumped to landfills. The advantage of SCGs it contains a lot of cellulose fibers that can be repurposed for new sustainable materials for a variety of applications.

Methods: In this study, we report a polylactic acid (PLA) composite filament with a high loading of oil-extracted spent coffee grounds (Ox-SCGs) up to 20% by weight and is three-dimensional (3D)-printable with a commercially available consumer-level 3D printer. The Ox-SCG-loaded PLA was found to be able to increase impact energy absorption. As a result, the PLA/Ox-SCG composite exhibited a 418.7% increase in toughness with a measure of 25.24 MJ/m3 at a 20 wt % Ox-SCG loading and only a 26% storage modulus reduction from the 100% PLA specimens at room temperature.

Results: The experimental results indicate that as a waste product from human consumptions and post biodiesel extraction, the Ox-SCG is proven to be a promising additive for composite property modification. Ox-SCG can not only increase the impact of toughness but also reduce the cost of overall 3D-printing materials. The applications of this composite materials are endless consider 3D printers are getting cheaper and the only limits are people’s imaginations