Valorization of coir pith for cellulose‐based polymer composites: Properties, modification strategies, processing, and applications

The global demand for sustainable, biodegradable, and economically viable alternatives to synthetic materials has intensified the research into plant‐based waste resources. Coir pith is a lignocellulosic byproduct generated during the extraction of coir fiber from coconut husks which remains largely underutilized. It is traditionally discarded or minimally used as low‐value mulch or compost. Coir pith is mostly accumulated near processing facilities posing environmental challenges due to land occupation and unmanaged degradation. The intrinsic properties such as high cellulose content, low bulk density, biodegradability, water retention capacity, and tensile strength make it an attractive value‐added material, particularly cellulose‐based polymer composite. This review provides a comprehensive analysis of the valorization of coir pith focusing on its transformation into functional materials through chemical, physical, and biological modifications. The main consideration is given to the pre‐treatment and surface modification techniques aimed at enhancing the interfacial adhesion between coir‐derived cellulose and polymer matrices. This review outlines the methods for isolating cellulose and developing composites with thermoplastic and thermosetting polymers. The resultant composites exhibit improved mechanical strength, thermal stability, durability, and environmental performance. The recent applications of coir pith‐based composites are critically reviewed, including their use in automotive interior components, building materials, biodegradable packaging, agricultural tools such as geotextiles, soil stabilizers, etc. This review highlights the potential of coir pith as a sustainable reinforcement material through a thorough evaluation of the material's properties, preparation techniques, and practical applications. It also outlines future research directions to advance its industrial utilization and promote circular economy practices in the agro‐industrial sector.