Additive manufacturing of PLA composites: impact of nanofillers on mechanical, fracture and thermal behavior

This study investigates how four nano-additives, namely graphene, amine-functionalized graphene, hexagonal boron nitride (hBN), and multi-walled carbon nanotubes, affect the properties of polylactic acid (PLA) used in material extrusion 3D printing. Each additive was added into the PLA at a low concentration of 0.1 wt.% to understand how it changes the mechanical, thermal, and fracture behavior of the printed material. The nanocomposite (NC) filaments were first extruded using a twin-screw extrusion and then 3D-printed into standardized specimens for testing and the samples were characterized using differential scanning calorimetry and Fourier transform infrared spectroscopy, along with tensile, flexural, impact, and fracture toughness tests. In addition, scanning electron microscopy was used to study the fracture surfaces and to understand the underlying failure mechanisms. The results showed that incorporating nano-additives improves the mechanical performance of PLA and the NCs exhibited enhancement of up to 86.08% in tensile strength, 92.41% in flexural strength, and 30% in impact strength, compared to neat PLA. Also, fracture toughness improved up to 69.46%, which indicates an improved resistance to deformation and crack propagation. Statistical evaluation using paired t-tests confirmed that these improvements are significant (p < 0.05). Amine-functionalized graphene NCs exhibited comparatively higher improvements across tensile, impact, and flexural properties among the NCs. These results indicate the potential suitability of the developed PLA NCs for lightweight automotive interior components and biodegradable packaging applications.