Hemp fiber and its bio-composites: a comprehensive review part I—characteristics and processing

Bio-based materials are becoming pivotal in creating a more sustainable future by mitigating the adverse effects of climate change, primarily motivated by fossil fuel consumption. Among these materials, natural fiber composites have seen a resurgence over the past two decades due to the demand for environmentally friendly alternatives that offer biodegradability and recyclability. These composites are widely used in industries such as automotive, packaging, sports, construction, and consumer products. Hemp fiber, in particular, is valued for its exceptional mechanical properties, including strength and stiffness comparable to glass fibers. This review consolidates research on hemp fiber–reinforced bio-composites, focusing on their structural characteristics, and performance enhancement techniques. Both chemical and physical modification strategies are employed to optimize fiber properties and improve compatibility with polymer matrices. Chemical methods involve using reagents to reduce fiber hydrophilicity, enhancing compatibility and coupling efficiency. Physical methods adjust fiber structure and surface properties to improve interfacial bonding, offering cleaner solutions. The paper examines recent advancements in these methods and discusses the mechanical properties of hemp fiber–reinforced bio-composites. It concludes with reflections on the future prospects for hemp fiber–reinforced polymer bio-composites.