Evaluation of the Mechanical Performance and Structural Characterization of Hybrid Green Composites Based on Periploca laevigata Aiton and Wool Natural Fibers

Abstract

The current research is focused on developing and evaluating new composite materials that are reinforced with natural fibers to enhance sustainability and create environmentally friendly composites. The use of both wool and Periploca laevigata Aiton fibers was chosen in the construction of the hybrid composite due to their similar organic composition, while also taking into account their different properties such as weight, density, and water absorption capabilities. This combination created a composite material that is not only lightweight but also has little water absorption. To further improve the quality of the wool, a treatment involving cold plasma has been carried out to enhance the bonding between individual fibers. Vacuum infusion technology is used during the manufacturing process to ensure the quality of the composite materials by eliminating trapped air, allowing for consistent purity in each repetition. The fibers used in this study include untreated wool fibers, NaOH-treated wool fibers, and cold plasma–treated wool fibers. Wool fibers were treated with a 5% sodium hydroxide solution for 30 min, resulting in fiber degradation. The concentration of the solution was gradually reduced until it reached a practical level of 0.1%. The hybrid composite incorporates wool that has undergone plasma treatments, which are crucial for removing organic contaminants from surfaces, strengthening the surface layer, and altering the chemical structure. The electric field applied had a strength of 9 kV and a frequency of 60 Hz. Atmospheric air was employed as the gas, with a flow rate of 800 L/min, and the fiber treatment lasted for 60 min. An analysis of natural fibers using Fourier transform infrared (FTIR) and X-ray diffraction (XRD) unveiled similarities in the organic structures and chemical bonds shared between Periploca laevigata Aiton fiber and wool fibers, despite their unique origins. While wool fibers are animal-derived, Periploca laevigata Aiton fibers stem from plants. By identifying these parallels, a hybrid composite material was formulated by combining plasma-treated wool fibers with Periploca laevigata fibers. This resulted in a significant improvement in the tensile, flexural, and compressive properties of the composite, establishing it as a promising avenue for enhancing mechanical performance. The PLAF-WLF hybrid composite exhibited a remarkable tensile strength of 26.02 MPa and Young’s modulus of 2.35 GPa, surpassing all other composites. In comparison, the PLAF composite demonstrated an impressive tensile strength of 20.1 MPa and Young’s modulus of 2.34 GPa. The PLAF-WLF hybrid composite exhibited the highest flexural load-bearing capacity of 253.15 N and Young’s modulus of 1.21 GPa. PLAF-WLF demonstrates a hybrid compressive strength of 59.56 MPa, while its Young’s modulus is 0.5 GPa. The mechanical analysis findings revealed that the hybrid composite incorporating cold plasma–treated wool fibers and Periploca laevigata Aiton fibers displayed superior mechanical characteristics. Additionally, the composite made of Periploca laevigata Aiton fibers, recognized for its lightweight nature, smooth surface, and high quality, showed notable mechanical properties as well.