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.