Mechanical properties of composites reinforced with lignocellulosic fibers have been researched in recent decades. Jute and mallow fibers are reinforcement alternatives, as they can contribute to increase the mechanical strength of composite materials. The present work aims to predict the Young’s modulus with application of continuous and aligned lignocellulosic fibers to be applied as reinforcement in polyester matrix. Fibers were manually separated and then arranged and aligned in the polyester matrix. Composites with addition 5, 15, and 25 vol% jute and mallow fibers were produced by vacuum-assisted hand lay-up/vaccum-bagging procedure. Samples were tested in tensile and the tensile strength, elasticity modulus, and deformation were determined. Results showed that the intrinsic Young’s modulus of the fibers was set at values around 17.95 and 11.72 GPa for jute and mallow fibers, respectively. Statistical analysis showed that composites reinforced with 15 and 25 vol% jute and mallow presented the highest values of tensile strength and Young’s modulus. The incorporation of 25 vol% of jute and mallow fibers increased the matrix Young’s modulus by 534% and 353%, respectively, effectively stiffening the composite material. Prediction models presented similar values for the Young’s modulus, showing that jute and mallow fibers might be used as potential reinforcement of polymeric matrices

Natural lignocellulosic fibers (NLFs) have in recent decades appeared as sustainable reinforcement alternatives to replace synthetic fibers in polymer composite material applications. In this work, for the first time, the periquiteira (Cochlospermum orinocense), a lesser known NLF from the Amazon region, was analyzed for its density and, by X-ray diffraction (XRD), to calculate the crystallinity index as well as the microfibrillar angle (MFA), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron analysis (SEM) and tensile strength. The apparent density found for the periquiteira fiber was 0.43 g/cm³, one of the NLF’s lowest. XRD analysis indicated a crystallinity index of 70.49% and MFA of 7.32°. The TGA disclosed thermal stability up to 250 °C. The FTIR analysis indicated the presence of functional groups characteristic of NLFs. The SEM morphological analysis revealed that the periquiteira fiber presents fine bundles of fibrils and a rough surface throughout its entire length. The average strength value of the periquiteira fiber was found as 178 MPa. These preliminary results indicate that the periquiteira fiber has the potential to be used as a reinforcing agent in polymeric matrices and can generate a lightweight composite with excellent mechanical properties that can be used in various industrial sectors.

This study investigates the combined influence of multi-walled carbon nanotube (MWCNT) concentration and structural architecture on the compressive behavior of fused filament fabrication (FFF)-printed PLA components. Neat PLA and PLA reinforced with 1.0 and 2.0 wt% carboxyl-functionalized MWCNTs were characterized by Raman spectroscopy, DSC, TGA, compression testing, statistical analysis, and scanning electron microscopy. Thermal characterization showed that MWCNT incorporation caused only minor changes in PLA thermal degradation while altering its crystallization behavior. For nearly solid specimens (90% infill), compressive strength increased from 53.4 MPa for neat PLA to 73.6 MPa at 2.0 wt% MWCNTs, although differences among MWCNT concentrations were not statistically significant. Honeycomb structures exhibited the highest mechanical performance at 1.0 wt% MWCNTs, reaching a compressive strength of 33.3 MPa, approximately 59% higher than that of neat PLA, with significant improvements in both compressive strength and elastic modulus. Two-way ANOVA revealed significant interactions between structural architecture and MWCNT concentration for both compressive strength and elastic modulus, demonstrating an architecture-dependent reinforcement response. SEM provided complementary morphological evidence consistent with the observed mechanical trends. These findings demonstrate that the most effective MWCNT concentration depends on structural architecture, highlighting the importance of simultaneously optimizing material composition and geometry in FFF-manufactured polymer nanocomposites.

With the advancement of Additive Manufacturing and its applications in various industrial segments, it becomes increasingly important to investigate the processability parameters associated with nano-reinforcement. This study examines the influence of infill parameters, such as patterns (hexagonal, triangular and concentric), shape (solid and honeycomb) and concentrations by mass of Carbon Nanotubes (CNTs) at 1.0 wt% and 2.0 wt% on the mechanical compression properties of the 3D printed material. In this sense, nanocomposites based on Polylactic Acid (PLA) matrix nano-reinforced by CNTs were characterized using the Scanning Electron Microscopy -SEM, X-ray Diffraction, Raman Spectroscopy techniques and mechanical analysis. The mechanical properties of both the matrix and the nanocomposites were determined through mechanical compression tests, in accordance with [1]. SEM revealed compacted regions, voids, and detachment in the structures. XRD characterization indicated PLA predominantly amorphous nature, while CNTs exhibited characteristic diffractions of carbon nanotubes. Raman characterization showcased bands and characteristic vibrations of CNTs and PLA, nanocomposites' vibrational modes combine those of CNTs and PLA. Mechanical compression analysis indicates a direct influence of infill pattern, shape, and nano-reinforcement. The triangle pattern outperformed other patterns, exhibiting a 15.03% increase compared to concentric and 8.8% compared to hexagon infill. In nanocomposites, all showed higher compressive strength than the matrix. For PLA/1.0%CNTs, strength was 16.8%, and for PLA/2.0%CNTs, it reached 39.2%. In honeycomb shapes with infill variations, the triangular pattern excelled with a 0.97% increase over concentric and 6.12% over hexagon patterns. Honeycomb results indicate a 59.6% increase for (PLA/1.0%CNTs) and a 0.48% increase for (PLA/2.0%CNTs) compared to the matrix. This study highlights 3D printing parameters, emphasizing the effectiveness of the triangular pattern and the enhanced strength with the addition of CNTs, providing insights to enhance products manufactured through Additive Manufacturing.

Natural lignocellulosic fibers (NLFs) replacing synthetic fibers have been used as reinforcement in polymer matrix composites. In this work, a lesser-known NLF endemic to the Amazon region, the envira fiber (Bocageopsis multiflora), was analyzed for its basic physical, thermochemical, morphological, and mechanical characteristics. In addition, epoxy matrix composites with 10, 20, 30, and 40 vol% of continuous and aligned envira fibers were evaluated by Fourier transform infrared spectroscopy (FTIR) and tensile tests. The results were statistically compared by ANOVA and Tukey’s test. The density found for the envira fiber was 0.23 g/cm³. The crystallinity index and microfibrilar angle obtained were 69.5% and 7.07°, respectively. Fiber thermal stability was found up to around 210 °C. FTIR confirmed the presence of functional groups characteristic of NLFs. Morphological analysis by SEM revealed that the envira fiber displayed fine bundles of fibrils and a rough surface along its length. The average strength value of the envira fiber was found to be 62 MPa. FTIR analysis of the composites confirmed the presence of the main constituents of the epoxy resin and NLFs. The tensile strength results indicated that the envira fiber addition increased the strength of the composites up to 40 vol%. The analysis of the fracture region revealed brittle aspects. These results indicate that envira fibers present potential reinforcement for polymer matrix composites and can be used in engineering applications, favored by their lightness and cost-effectiveness.