The influence of coffee ground waste on the thermal and mechanical characteristics of polymer-based 3D printing filament materials

Abstrak

The development of polymer-based 3D printing filaments is challenged by the need for greater mechanical strength and thermal stability. Coffee grounds waste was selected as a filler to enhance the properties of polylactic acid (PLA), a widely used polymer filament. The coffee grounds were treated with NaOH to remove lignin, hemicellulose, and impurities, thereby improving their compatibility with the PLA matrix. The treated filler was incorporated into the polymer matrix at 2%- 8% w/w and molded into standard tensile test specimens according to ASTM D638. Mechanical testing and thermal analysis were performed to assess the performance of the resulting biocomposites. Results indicate that increasing the filler content in 2% w/w increments up to 8% w/w enhances tensile strength by approximately 1.5 MPa, tensile strain by 0.002, and elastic modulus by 30.378 MPa. Thermal analysis also shows an increase in glass transition temperature (Tg) from 59°C to 66°C and a rise in degradation peak temperature from 335.9°C to 371.1°C. These enhancements are attributed to improved interfacial adhesion between the treated filler and the PLA matrix, which restricts polymer chain mobility. Alkali-treated coffee grounds waste thus represents a promising sustainable filler for enhancing the mechanical and thermal performance of polymer-based 3D printing filaments.