Low-Cost Coir Fiber Composite with Integrated Strength and Toughness

With the growing environmental problems and depletion of petroleum resources, there is an urgent demand for the biorenewable, sustainable, and environmentally friendly composite materials. Here, we report a green coir fiber composite with specific mechanical properties superior to that of other reported natural fiber/polymer composites. After treatment, both strength and toughness of the composite fiber were substantially improved (91.13% and 175.7% higher than that of untreated counterpart), where exposed cellulose nanofibrils and stacking layer formed by NaOH infusion and the hydroxylcontaining hydrophilic poly(vinyl alcohol) coating play a crucial role in physicochemical interaction and thereby mechanical enhancement. By observing the process of the micro/nanostructure evolution, the strengthened mechanism from nanoscale to macroscale was demonstrated. We believe that this strategy could open new insights into the design of strong and sustainable composite fiber for further practical applications, such as textile, home furnishings, and industrial products.