High‐Strength, Environmentally Stable Wood Fiber/Polyamide/Polyethylene Composites Enabled by High‐Temperature Compatibilization With Triple‐Crosslinked Interface

ABSTRACT Introducing a binary matrix of engineering and general‐purpose plastics is an effective strategy to synergistically enhance the mechanical performance and cost‐effectiveness of wood fiber‐reinforced composites by leveraging the complementary properties of different polymers. However, achieving such hybrid composite structures often suffers from processing differences and interfacial incompatibility among components. Herein, a straightforward and scalable high‐temperature compatibilization strategy is proposed to fabricate wood fiber/polyamide/polyethylene composites (WPAECs) with a triple‐crosslinked network interface, through reactive blending of the matrix followed by optimization of processing temperature. The WPAECs constructed from polyamide/polyethylene matrix and hydrothermally treated wood fibers can achieve mechanical strengthening by the uniform internal structure and triple cross‐linking interactions (physical interlocking, covalent bonds, and hydrogen bonds), resulting in high flexural strength of 72.33 MPa while maintaining a low density of 1.10 g cm −3 . Moreover, the mechanical strength of WPAECs can be further enhanced by optimizing the wood fiber content. WPAECs also exhibit advantageous environmental stability, including low‐temperature toughness, low water absorption rate (below 2.33%), and good heat resistance. Coupled with abundant raw materials, ease of processing, and scalable and recyclable fabrication, WPAECs provide a promising pathway toward high‐performance and sustainable structural component applications.