Ecocomposite Filaments from Spent Coffee Grounds for FFF 3D Printing: Material Properties and Printability

Area of Science:

• Materials Science
• Polymer Science
• Sustainable Materials

Background:

• Polylactic acid (PLA) is a biodegradable polymer with growing applications in 3D printing.
• There is increasing interest in utilizing waste materials like spent coffee grounds (SCGs) to create functional composites.
• Investigating the effects of SCG incorporation on PLA properties is crucial for developing sustainable 3D printing materials.

Purpose of the Study:

• To evaluate the impact of spent coffee grounds (SCGs) on the thermal, physical, and mechanical properties of polylactic acid (PLA) filaments and 3D-printed parts.
• To assess the feasibility of using SCGs as a filler in PLA for 3D printing applications.
• To understand the property trade-offs associated with SCG incorporation in PLA composites.

Main Methods:

• Spent coffee grounds (SCGs) were compounded with polylactic acid (PLA) to create filaments.
• Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to assess thermal properties.
• Tensile testing was performed on filaments and 3D-printed parts.
• Physical properties such as density and moisture uptake were measured for printed parts.

Main Results:

• SCG addition increased PLA crystallinity and slightly decreased its glass transition temperature.
• Thermogravimetric analysis confirmed thermal stability above processing temperatures.
• Filament tensile strength and stiffness decreased, while elongation at break was minimally affected.
• 3D-printed parts showed reduced density, increased moisture absorption, and decreased tensile, flexural, and impact strengths.
• Tensile modulus and elongation at break for printed parts remained statistically similar within the tested SCG concentration range (0-20 wt%).

Conclusions:

• Spent coffee grounds (SCGs) can be effectively incorporated into polylactic acid (PLA) to modify crystallinity, color, and density.
• SCG-PLA composites offer potential for sustainable 3D printing but involve trade-offs in mechanical strength and impact performance.
• Further research may explore optimizing SCG processing and formulation to mitigate strength reductions in 3D-printed components.