This study evaluates the hybridization effect of S2-glass/aramid on polyurethane (PU) composites produced by vacuum infusion. Different laminates were produced with similar thickness (around 2.5 mm), using, as reinforcement, only aramid fabrics (five layers, named as K₅) or only S2-glass fabrics (eight layers, named as G₈). Furthermore, hybridization was obtained by manufacturing symmetrical hybrid inter-ply laminates, with four S2-glass layers and two of aramid, (G₂K)_S and (KG₂)_S. The mechanical response of the laminates was evaluated in tensile, interlaminar shear strength, dynamical mechanical analysis and quasi-static indentation tests, and related to their morphological characteristics. The main results show that the pure glass composites presented less voids, but a higher density as well as higher tensile stiffness and strength. The aramid laminates showed a high capability for absorbing impact energy (ca. 30% higher than the pure glass laminates), and the hybrid laminates had intermediate properties. More importantly, this work shows the possibility of using a polyurethane matrix for vacuum infusion processing, effective even for aramid/S2-glass hybrid composites with thermoset polyurethane resin. This study is therefore promising for impact absorption in applications such as protective armor. The studied hybrid laminate may display a suitable set of properties and greater energy absorption capability and penetration resistance for impact applications.

Fiber-reinforced cement composites, particularly those incorporating natural fibers like cellulose, have gained attention for their potential towards more sustainable construction. However, natural fibers present inherent deficiencies in mechanical properties and can benefit from hybridization with carbon fibers. This study focuses on the incorporation of cellulose and carbon fibers, in varying contents, into fibrocement composites, employing a Response Surface Methodology (RSM) to optimize the material characteristics. The methodology involves testing, encompassing flexural tensile, compression, and fracture toughness tests. The results indicate an increasing trend in flexural strength for higher carbon fiber content, peaking near 5%. A plateau in flexural strength is observed between 1.2% and 3.6% carbon fiber content, suggesting a range where mechanical properties stabilize. Compressive strength shows a plateau between 1.2 and 3.6% and reaches its highest value (≈33 MPa) at a carbon fiber content greater than 4.8%, and fracture toughness above 320 MPa·m^1/2 is achieved with carbon fiber content above 3.6%. This study offers insights into optimizing the synergistic effects of cellulose and carbon fibers in fibrocement composites.

This study investigates the fibers of tucum (Bactris setosa Mart.), a palm species native to the Atlantic Forest. The fibers manually extracted from tucum leaves were characterized to determine important properties that help with the recognition of the material. The fibers were also subjected to pre-bleaching to evaluate their dyeing potential. The extraction and characterization of these fibers revealed excellent properties, making this material suitable not only for manufacturing high-quality textile products but also for various technical and engineering applications. The characterization techniques included SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared Spectroscopy), TGA (Thermogravimetric Analysis), and tensile strength tests. These analyses showed that tucum fibers possess desirable properties, such as high tensile strength, with values comparable to linen but with a much finer diameter. The fibers also demonstrated good affinity for dyes, comparable to cotton fibers. An SEM analysis revealed a rough surface, with superficial phytoliths contributing to their excellent mechanical strength. FTIR presented a spectrum compatible with cellulose, confirming its main composition and highly hydrophilic nature. The dyeing tests indicated that tucum fibers can be successfully dyed with industrial direct dyes, showing good color yield and uniformity. This study highlights the potential of tucum fibers as a renewable, biodegradable, and sustainable alternative for the transformation industry, promoting waste valorization.