Mechanical Characterization of Fused Deposition Modeling‐Printed Wood‐Polylactic Acid Composites Under Water Conditioning

ABSTRACT Natural fiber‐reinforced thermoplastic composites have gained increasing attention due to their sustainability. Additive manufacturing, particularly Fused Deposition Modeling (FDM), enables the fabrication of such composites with complex geometries. This study investigates the mechanical behavior of wood‐polylactic acid (PLA) composites fabricated via FDM, focusing on their tensile and fracture properties under different water absorption durations. Results indicate that wood‐PLA exhibits reduced tensile strength and stiffness compared to pure PLA. The tensile strength for wood‐PLA was 23.4 MPa, which was significantly lower than the strength of the PLA (54.6 MPa). However, the wood‐PLA showed enhanced strain energy density in the tensile test, measuring 1.41 times greater than the PLA, and higher energy absorption ability in the Single Edged Notched Bending (SENB) test. Water uptake induced plasticisation effects in the wood‐PLA composites, resulting in a 20% reduction in strength and a 10% decrease in elastic modulus after 15 days. Moreover, elongation at break increased by 66%, contributing to a 48% improvement in energy absorption. Notably, these effects are reversible upon redrying, suggesting that water primarily acts as an external plasticizer. The study highlights the mechanical response of wood‐PLA composites and provides insights into their structural integrity in humid environments.