Investigation of thermo-mechanical and viscoelastic properties of 3D-printed Morinda citrifolia particle reinforced poly(lactic acid) composites

The current study focuses on the development of innovative bio-based filaments using new natural lignocellulosic particles obtained from the bark of the Morinda citrifolia L. plant as reinforcement. Polylactic acid (PLA 4043D) filaments with a diameter of 1.75 mm were produced by varying the volume fraction of M. citrifolia bark particles (MCBP) in three compositions (i.e., 0%, 3%, and 6%). These filaments were then used to print test specimens, which underwent quasi-static mechanical tests (i.e., tensile and flexural; thermal characterization, thermo-mechanical tests, and visco-elastic analysis). The experimental findings demonstrated a remarkable improvement in the tensile strength (i.e., +15%) when the PLA was reinforced with 6% in volume of lignocellulosic particles. Additionally, 3% MCBP and 6% MCBP composites showed substantial increases in flexural strength and modulus (i.e., +25% and +34%), respectively; in comparison to the neat matrix. Moreover, the 3D-printed composites exhibited significant enhancements in storage modulus, glass transition temperature, and structural stability at elevated temperatures. Hence, this work highlights the potential of the developed bio-based filaments as feedstock filament material, enabling the production of various customized lightweight products in the automotive and sports industries like cycling helmets, protective guards, knee guards, etc.