In-situ lignin regeneration strategy to improve the interfacial combination, mechanical properties and stabilities of wood-plastic composites

This work presented an in-situ lignin regeneration strategy to improve the interfacial combination among wood-plastic composites (WPCs) and realize synchronous improvements of their static/dynamic mechanical properties and stabilities. Taking corn stover (CS) as a model, the lignin in them were dissolved in deep eutectic solvents (DES) and regenerated in water, during which the lignin migrated from inside to surfaces of CS. Ascribing to the uniform loading of hydrophobic and supramolecular lignin on the surfaces of CS, their interfacial combination with high density polyethylene (HDPE) were optimized, and the resultant WPCs exhibited synchronous increases of static mechanical properties (maximal increases of tensile strength ∼4.42 %, tensile toughness ∼90.24 %, flexure strength ∼41.20 %, and impact strength ∼18.82 %), dynamic strengths and stabilities (e.g., −30 °C–60 °C, humidity, and UV aging). Moreover, the regenerated lignin on CS also facilitated their combination with functional components (e.g., carbon black), and exhibited a conductivity of ∼3.97 S/m with 20 wt% of carbon black. Thus, this work paved a green and efficient way to turn wood residues into composites with high mechanical strength, stabilities, and potential functionalities, which were promising to expanded their applications as structural and functional materials.