PLA/Coffee Grounds Composite for 3D Printing and Its Properties

Abstract

Coffee is one of the most popular beverages in the world. It generates a waste known as coffee grounds. In this work, changes in mechanical properties, crystallinity index, and DSC characteristics of PLA/coffee grounds with different dosages were analyzed by XRD, DSC, and mechanical property tests. Statistical analysis showed that the modulus of rupture of PLA/coffee grounds 3D printing materials was maximal at 109.07 MPa and 3604 MPa when 3% coffee grounds were added. The tensile strength of the untreated PLA complex was 49.99 MPa, and the tensile strength increased from 49.99 MPa to 51.28 MPa after 3% coffee grounds were added. However, there was no significant difference between the PLA complex and PLA/coffee grounds 3D printing materials when the additions were lower than 3%. The statistical analysis showed that when the coffee grounds additions increased from 5% to 7%, the tensile strength of PLA/coffee grounds 3D printing products significantly decreased. For example, the tensile strength decreased from 49.99 MPa to 26.45 MPa with addition of 7% coffee grounds. The difference between the glass transition, cold crystallization, and melting temperatures of PLA coffee grounds 3D printing materials was almost negligible, which indicates that the thermal properties of PLA coffee grounds 3D printing materials are comparable to those of PLA, and that the processing temperature and FDM printing temperature of the PLA filament are suitable for application to the PLA coffee grounds 3D printing material system.

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

“…Similarly, elongation at break (Figure d) shows comparable results for the two PLA/CM formulations, i.e., 2.1% (95PLA5CM) and 2% (90PLA10CM). Although SCGs make the 3D printed formulations less stiff compared to PLA, higher values of elastic modulus, ultimate tensile strength, and elongation at break were obtained compared to previous works from the literature. , This fact is consistent with the results from the thermal characterization, showing no significant degradation and better printability due to the decrease in viscosity. Using pellet feedstock reduced the processing steps to obtain the raw material, i.e., extruding 3D printing filament, limiting the thermomechanical degradation of a further extrusion cycle on the mechanical properties …”

“…X-ray diffraction tests investigated the crystallization behavior of 3D printed samples and the influence of SCGs on the polymer matrix. In general, PLA manifests a broad hump of crystallinity in the range of 2θ = 10–25°, typical of amorphous polymers. , This fact is confirmed by the results of the 100PLA0CM formulation. Similarly, the 3D printed formulations showed the same range (Figure S3, Supporting Information).…”

Mechanical and Thermal Properties of 3D‐Printed Biocomposites of Polylactic Acid and Thermally Modified Wood Flour with Silver Nanoparticles

“…Its melting point is less than 200 °C, and this temperature is lower than the thermal degradation temperature of wood. [ 3 ]…”

“…The use of polylactic acid (PLA) polymers in the filament industry has increased considerably in the last decade due to their unique properties, such as their biodegradability, compostability, and processability, and good mechanical properties; however, they are brittle, with low crack initiation energy and low toughness. [2,3] PLA is a semicrystalline polymer made from fermented plant starch, particularly corn starch. Its melting point is less than 200 °C, and this temperature is lower than the thermal degradation temperature of wood.…”

“…Its melting point is less than 200 °C, and this temperature is lower than the thermal degradation temperature of wood. [3] Wood is a sustainable and environmentally friendly reinforcing filler for polymer composites. There is an increasing trend of using wood as a filler in thermoplastic filaments printed using 3D printers.…”