Thermal, Structural and Chemical Properties of Natural Bark Fibers for Use in Advanced Polymer Composite Reinforcement

The demand for sustainable and high-performance reinforcement materials has led to extensive research on natural fibers derived from plant sources. Among these, bark fibers have emerged as a promising reinforcement for polymer composites due to their unique combination of mechanical strength, low density, renewability, and cost-effectiveness. However, the effective utilization of bark fibers in high-performance applications requires a comprehensive understanding of their thermal, structural, and chemical characteristics. This paper presents an in-depth review of the advanced characterization of natural bark fibers and their suitability for polymer composite reinforcement. It explores various analytical methods such as thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM), which provide insights into the fiber’s chemical composition, crystallinity, surface morphology, and thermal degradation behavior. The study also discusses how alkali and silane treatments modify the fiber surface and improve fiber–matrix adhesion in polymer composites. The results of such characterization are crucial in optimizing processing parameters and enhancing the mechanical and thermal performance of bark fiber–reinforced composites for structural, automotive, and aerospace applications.