Thermally modified beech wood in polylactic acid filaments for 3D printing

The production of biocomposites often aims to achieve environmental benefits by replacing traditional synthetic oil-based materials with components from renewable biological sources. In this study, filaments for 3D printing were produced from different mass fractions of beech wood (thermally modified and unmodified) and polylactic acid (PLA), used for specimens produced by 3D printing and injection moulding. Thermal modification (TM) of wood is a method often used to improve the hygroscopic properties of wood. Although TM has been used industrially for a few decades, its effects on incorporating modified wood particles into the PLA matrix are still poorly understood. This study aimed to evaluate the effects of TM beech wood on the morphology and encapsulation of wood particles in the PLA matrix, comparing thermally modified and unmodified beech wood. This interdisciplinary research involves the analysis of wood-PLA composite specimens to understand their composition, structure and mechanical properties. Four measurement methods were used: microscopy, surface roughness, dynamic mechanical analysis (DMA) and hyperspectral imaging (HSI). The results show that increasing wood content enhances the storage and loss modulus, while TM wood composites exhibit better surface quality, and enhanced dispersion. The glass transition temperature remained consistent, but decreased slightly with higher TM wood content.