Characterization of Mediterranean agro waste fibers for sustainable energy-saving bio-materials: thermal stability, conductivity, inherent characteristics, and mechanical performance

Discovering new renewable materials and utilizing the available natural resources are recently emphasized to develop better bio-materials for the near future bio-products and cleaner production theme. The shift toward sustainability involves the exploration of natural and bio-based products for modern societies. This study aims to investigate and revealing the potential of various Mediterranean natural fiber species for bio-materials suitable for various industrial applications including thermal insulation products for energy-saving schemes. Several lignocellulosic fibers form different plant species were investigated and characterized regarding their inherent physical characteristics including density, moisture content, thermal stability, mechanical performance, chemical absorption pattern, and thermal conductivity. Thermal properties, including thermal stability utilizing thermogravimetric analysis (TGA) and thermal conductivity were examined to reveal their potential for insulation and energy-saving applications. Mechanical properties of fibers were also evaluated for the determination of critical parameters including modulus of elasticity, mechanical strain, and ultimate tensile strength. Fourier Transform infrared spectroscopy (FTIR) analysis was also conducted to address their chemical structure and performance relationship as well as to analyze the absorption coefficient for each type of fibers. Findings revealed that fibers with lower moisture content exhibited better thermal stability. Hay fibers showed the lowest moisture content and demonstrated superior mechanical properties regarding ultimate tensile strength. In contrast, tomato fiber was found to have the highest moisture content. Moreover, it was found that all considered Mediterranean fiber types have demonstrated relative low density offering advantages for various industrial applications. Regarding thermal conductivity, hay and almond fibers exhibited the lowest values, with thermal conductivity coefficients of 0.036 W/(m·K) and 0.035 W/(m·K), respectively, while tomato fibers display the highest thermal conductivity value, approximately 0.079 W/(m·K). The low thermal conductivity observed in such fibers highlights their potential for thermal insulation and energy-saving applications.