Formaldehyde-free binder of natural rubber latex and lignin for sugarcane bagasse fiber composite plates

The rising demand for sustainable alternatives to conventional formaldehyde-containing binders has accelerated the development of renewable adhesives for environmentally friendly wood-inspired composites (WIC). Addressing a gap in the study of elastomeric matrices, this work introduces a novel WIC utilizing sugarcane bagasse fibers (SBF) bonded by an innovative bio-based adhesive (ADV) composed of natural rubber latex (NR) and alkali lignin. The WIC materials were fabricated via a straightforward hot-pressing process. Critically, the ADV binder was the key innovation, yielding composites with up to 60 % higher performance compared to formulations using only NR. Furthermore, varying the SBF content enabled significant modulation of the material properties, achieving a Young’s modulus of 5–35 MPa, yield strength of 0.25–1.25 MPa, and hardness of 30–90 IRHD. Abrasion resistance was also enhanced by nearly 40 %. Scanning electron microscopy revealed that lignin in the ADV improved the wettability and mechanical anchoring of the SBF within the matrix. Complementary X-ray microtomography further demonstrated a reduction in porosity in the ADV-WIC, while dynamic mechanical analysis suggested improved interfacial compatibility due to lignin incorporation in ADV. These results demonstrate a tunable, high-performance, and formaldehyde-free WIC material with strong potential for structural and coating applications as a green alternative to conventional wood-based products.