Metallic nanoparticles with virucidal properties dispersed in a polymeric matrix have gained prominence in the scientific community as a rapid and effective alternative that employs the additive manufacturing (AM) or 3D printing method. This study aims to produce filaments for 3D printing using polymer nanocomposites based on polylactic acid (PLA) and copper nanoparticles (CuNPs) in different proportions. The virucidal activity of various proportions of nanoparticles in PLA was investigated. The composites were produced following a mixture design (DOE) with concentrations ranging from 1% to 2% copper nanoparticles, which were blended with PLA using a single-screw extruder. The samples were characterized by thermogravimetry (TG), differential scanning calorimetry (DSC), tensile strength testing, and fracture analysis using scanning electron microscopy (SEM). A thermal analysis of the composites indicated that the CuNPs contributed to an increase in the degradation temperature and crystallization of the PLA. Sample S7 (1.25% of CuNPs) exhibited a 4% increase in the degradation temperature compared to pure PLA. The best tensile strength results were observed in sample S7 (1.25% of CuNPs), 30% more than sample S3 (1.33% of CuNPs) due to good material cohesion, as evidenced by microscopy analyses. Regarding virucidal analyses, most composites demonstrated virus inhibition activity.

3D printing with biodegradable polymers such as polylactic acid (PLA) is a sustainable alternative to conventional petroleum-derived plastics. However, improving the mechanical properties of PLA remains a challenge. This study explores the incorporation of chemically treated hemp fibers to improve the interfacial adhesion and mechanical strength of PLA filaments. Samples with PLA and hemp were prepared by subjecting the fibers to cationization treatment with (3-chloro-hydroxypropyl) tri-methylammonium (EPTA) and functionalization with glycidyl methacrylate (GMA). EPTA improves adhesion mainly through surface modification, increasing reactive functional groups in cellulose, while GMA improves interfacial adhesion by forming covalent bonds with both the fiber and PLA and improves the dispersion of the fiber in the matrix. Mechanical properties were evaluated by tensile testing, as well as fracture morphology by scanning electron microscopy (SEM) and X-ray energy dispersive analysis (EDS). The results showed that the addition of untreated hemp significantly reduced the strength of PLA, but cationization with EPTA improved interfacial adhesion and increased tensile strength by 615%. The combination of treated fibers and GMA further optimized the mechanical properties, reaching values similar to pure PLA. These findings indicate that the chemical modification of natural fibers facilitates their integration into PLA filaments for 3D printing, promoting sustainable materials without compromising mechanical performance.

This study explores the production of composites based on polylactic acid (PLA) reinforced with microcrystalline cellulose (MCC), using Additive Manufacturing technology via LCD. Polylactic acid, being biodegradable and possessing good mechanical properties, was combined with microcrystalline cellulose, which has a high modulus of elasticity, aiming to further improve its performance. Composites with different microcrystalline cellulose contents (1, 3, 5, and 10%) were obtained and compared to pure PLA. Characterization involved thermal, mechanical, morphological, and structural tests. The results showed that the addition of microcrystalline cellulose increases hardness, tensile strength, and modulus of elasticity. Scanning electron microscopy revealed more heterogeneous fracture surfaces in the composites compared to pure polylactic acid. Thermal stability varies according to the microcrystalline cellulose content, with increased degradation observed in some samples, reaching 1%. Increased water absorption was also detected with increasing microcrystalline cellulose concentration, indicating potential limitations in humid environments. The incorporation of microcrystalline cellulose, especially at moderate concentrations such as 3%, proved to be an effective strategy for improving the mechanical properties of polylactic acid.