Highly Reinforced and Toughened Polylactic Acid Composites by Aligned Cellulose Macrofibers for Triboelectric Nanogenerator Applications

Driven by the global demand for sustainable development, lightweight biobased composites have demonstrated significant potential. However, current biobased materials are unable to achieve the high strength and toughness exhibited by conventional synthetic materials. This work presents a simple and effective strategy to fabricate ultrastrong and tough polylactic acid–based composites through the incorporation of highly aligned cellulose macrofibers (CMs). The CMs, composed of tightly stacked and oriented cellulose, were extracted from natural bamboo by delignification treatment, and the surfaces were functionalized with epoxy groups. By combining high-orientation fiber alignment with surface modification, we established a continuous stress-transfer network. The composites achieved an exceptional tensile strength of 315.1 MPa and impact toughness of 28.82 kJ/m2, while maintaining a low density of 1.08 g/cm3, representing a very advanced performance in lightweight biobased composites. Furthermore, the wind-driven triboelectric nanogenerators fabricated using the composite maintain a stable output over 1 million operational cycles under continuous wind vibration. These results highlight the promising applicability of the developed composites in energy conversion systems requiring both mechanical robustness and environmental sustainability.