Cellulosic sunnhemp fibres and their role in polymer composites-A comprehensive review

Sunnhemp, an ancient yet underexplored plant, is emerging as a multifunctional resource capable of nourishing soils, weaving sustainable textiles, and reinforcing eco-friendly polymer composites for a greener future. Among the various options being explored, Crotalaria juncea (sunnhemp) stands out as a versatile green-manuring crop with a multitude of applications. The plant has gained significant importance due to its economic and ecological value, offering benefits such as intercropping, CO₂ sequestration, wind-breaking, nematode resistance, livestock feed, nitrogen fixation, biomass generation, and textile-grade bast fibre production. The high-quality bast fibres make it an ideal candidate for sustainable textile fibre production, requiring only the stem part of the plant for fibre extraction while the remaining biomass is utilizable for soil enrichment or energy generation. With its low density, optimal cellulose content, and good tensile strength, sunnhemp fibre is suitable not only for technical and traditional textiles but also as a renewable reinforcement material in polymer composites, including automotive parts, construction panels, and packaging. This paper provides an overview of sunnhemp as a sustainable crop, covering botanical description, growth characteristics, cultivation, production, current scenario, and applications in agriculture, textiles, and composites, with emphasis on challenges, barriers in fibre extraction and processing, and future prospects.