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. Highlights: Innovative bio-based filaments are developed for FDM 3D printing. Morinda citrifolia bark particles (MCBPs) reduce warping risk in PLA printing. The hot crystallization enthalpy of PLA increases with the addition of MCBP. 6% MCBP-PLA exhibits the best mechanical performances. MCBP reinforcement reduces the thermal expansion of PLA.