In order to increase the robustness of natural fiber (NFR), hybridization with synthetic fibers is crucial. The widespread usage of hybrid composites (HCs) in modern structural applications reflects their increasing popularity. When compared to non-hybrid composites, hybridization offers additional advantages due to its combination of inexpensive, high-quality fibers that enhance the properties of a composite without a significant increase in cost. Although the mechanical properties (MP) of various HCs have not yet been explored in depth, it is one of the benefits brought by hybridization. This article reviews and analyzes the latest information on the MP of HCs composed of synthetic and natural fibers. It also conducts a critical analysis of the important information that can be gleaned from published research on the factors that influence the morphological characteristics, physical-mechanical attributes, benefits, and challenges associated with NFR-reinforced composites. As a result, this compilation provides an in-depth critical analysis of innovative treatment techniques that are suitable for enhancing interfacial bonding (IB) between NF and polymer matrix (PM) and their MP. Additionally, each category of HCs, including thermoset and thermoplastic polymers as well as bionanocomposites, is discussed. Overall, this comprehensive study demonstrates that lignocellulosic fibers are widely employed in composite reinforcement and confirms that the hybridization of various reinforcing fibers has synergistic impacts on the mechanical properties of HCs.
