3D printed sustainable biocomposites based on PLA reinforced with waste vegetal biomasses of the Mediterranean area

The transition toward sustainable materials has generated growing interest in biocomposites that combine bio-based polymers with natural fillers. In this study, polylactic acid (PLA) was reinforced with two biomass fillers, specifically Ailanthus altissima (AIL) and Chamaerops humilis (CH), incorporated at 10 and 20 wt%, and processed via melt extrusion followed by Fused Deposition Modeling (FDM) to obtain printable filaments. A comprehensive characterization of mechanical, morphological, thermal, and environmental properties was carried out. Although all biocomposites showed moderate reductions in flexural and impact strength compared with neat PLA, their tensile strength and elongation at break improved significantly, particularly in AIL-based composites. SEM analysis revealed superior filler dispersion and matrix-filler adhesion in AIL systems, correlating with enhanced ductility and reduced void content. The introduction of the ''intraphase'' parameter (i.e., polymeric phase filling the pores) quantified by pycnometry and supported by FTIR-ATR analysis allowed the description of the degree of matrix penetration into filler lumens and its effect on mechanical performance. AIL-based composites exhibited higher intraphase values and retained more polymer within filler voids, resulting in better stress transfer and reduced brittleness. Additionally, a preliminary assessment of sustainability benefit highlighted significant environmental advances, with CO2 savings up to 5.4 kg per 100 kg of product for AIL20 due to both the renewable origin of PLA and the valorization of invasive or waste biomasses. These findings suggest that AIL and CH fillers represented viable and sustainable alternatives to conventional reinforcements in FDM-printed PLA composites.