PLA Feedstock Filled with Spent Coffee Grounds for New Product Applications with Large-Format Material Extrusion...

Area of Science:

• Materials Science
• Additive Manufacturing
• Sustainable Materials

Background:

• Food waste, like spent coffee grounds (SCGs), presents a significant disposal challenge.
• Valorization of SCGs aligns with circular economy and bioeconomy principles.
• Large-format pellet extrusion 3D printing offers potential for scaling biomass-polymer composite applications.

Purpose of the Study:

• Investigate the properties of polylactic acid (PLA)/SCG composites for large-format pellet extrusion 3D printing.
• Assess the thermal, rheological, and mechanical performance of these novel materials.
• Demonstrate the feasibility of using PLA/SCG composites in large-scale additive manufacturing.

Main Methods:

• Formulation of PLA/SCG composites with varying SCG content.
• Characterization of thermal stability, rheological behavior, and mechanical properties (tensile strength, elongation at break).
• Utilized large-format pellet extrusion 3D printing for fabricating complex parts, including non-planar slicing techniques.

Main Results:

• PLA/SCG composites showed minimal thermal degradation at typical PLA 3D printing temperatures (~190 °C).
• Increased SCG content had limited impact on composite crystallinity.
• Reduced viscosity from SCGs improved printability and layer adhesion, leading to enhanced tensile strength and elongation at break.
• Pellet feedstock minimized thermomechanical degradation by eliminating filament extrusion.

Conclusions:

• PLA/SCG composites are suitable for large-format pellet extrusion 3D printing.
• These sustainable materials offer improved mechanical performance compared to existing biomass-polymer composites.
• The study validates the use of large-format pellet extrusion 3D printing for scaling up the application of biomass-filled polymers, including the creation of large-scale products like furniture.