The removal of rice straw extractives increases the interphase adhesion between rice straw and the high-density polyethylene (HDPE) matrix, while eradicating the inner defects of rice straw/HDPE composites. This study investigated the effect of rice straw extractives removal on the dimensional stability (water uptake and thermal expansion), dynamic mechanical properties, creep, and stress relaxation of rice straw/HDPE composites. Cold water (CW), hot water (HW), and 1% alkaline solution (AL) extraction methods were utilized to remove rice straw extractives. Extracted and unextracted rice straws were mixed with HDPE, maleated polyethylene (MAPE), and Polyethylene wax to prepare composites via extrusion. Removal of rice straw extractives significantly improved the dimensional stability, dynamic mechanical properties, and creep and stress relaxation of rice straw/HDPE composites, with the exception of the thickness swelling of the AL/HDPE and the thermal expansion of the rice straw/HDPE composites. HW/HDPE exhibited the best comprehensive performance.

This study presents the design and fabrication of a glass fiber–poplar veneer composite plate, investigating how varying interlayer configurations of glass fiber (single- and double-layer) and the arrangement of poplar veneer layers (odd and even) impact the mechanical and thermal insulation characteristics of these composite plates. Compared to plywood made from natural wood, glass fiber significantly improved the properties of fast-growing poplar plywood. The highest impact strength increased by 3.62 times, while the flexural strength increased by 26.22% and the tensile strength by 29.66%. The thermal diffusion coefficient of the experimental group decreased by 40.74%, indicating better insulation. Interestingly, single-layer glass fiber is superior to a double-layer structure in terms of thermal insulation. An optimal interlayer structure was identified, comprising one veneer layer between two layers of glass fiber cloth, repeated three times. Abaqus 2019 was used for finite element analysis (FEA). The simulation results agree with the experimental data to within 5%. These findings confirm the importance of structural configuration in determining the properties of composite materials, providing a theoretical basis for the structural design of fiber–reinforced composite materials.

Wood, a renewable and sustainable resource with a hierarchical porous structure, exhibits significant potential for functional composites through integration with polymers. Wood/polymer composites are typically fabricated either via polymer impregnation into wood or through blending of wood powder with thermoplastic polymers to produce wood–plastic composites (WPCs). However, conventional thermosetting polymers cannot be reshaped or reprocessed, while thermoplastic polyolefins often exhibit poor compatibility with wood powder. Dynamic covalent polymer networks (DCPNs), which incorporate reversible covalent bonds into thermoset matrices, enable network reconfiguration in response to external stimuli such as heat. Replacing conventional polymers with DCPNs in delignified wood yields transparent wood with programmable shape-memory, photo-luminescent, and thermochromic properties, enabling the fabrication of advanced materials. DCPN-impregnated delignified wood is also reprocessable and degradable. Similarly, incorporating DCPNs into carbonized wood produces electrode materials with enhanced plasticity, shape-memory behavior, reshaping ability, and self-healing properties. DCPNs can replace thermoplastic polyolefins as matrices in WPCs. Consequently, repairable and reprocessable wood powder/DCPN composites can be fabricated with potential for carbon storage applications. This mini-review summarizes recent advances in wood/DCPN composites, focusing on two main fabrication approaches: DCPN impregnation into delignified wood and blending of DCPNs with wood powder. Wood/DCPN composites combine the characteristics of wood and dynamic DCPNs and have the potential to become an efficient, eco-friendly, and sustainable form of processing and utilization of wood.

In this study, alkali-treated wood flour/dynamic polyurethane composites were successfully prepared through a solvent-free one-pot method and in situ polymerization. The effects of the alkaline treatment process, changes in the flexible long-chain content in the dynamic polyurethane system, and the wood flour filling amount on the interface’s bonding, mechanical, and reprocessing properties were investigated. Partial removal of lignin and hemicellulose from the alkali-treated wood flour enhanced rigidity and improved interface bonding and mechanical strength when combined with dynamic polyurethane. The tensile strength was improved from 5.65–11.00 MPa to 13.08–23.53 MPa. As the composite matrix, dynamic polyurethane could not easily infiltrate all wood flour particles when its content was low or its fluidity was poor. Conversely, excessive content or overly high fluidity led to leakage and the formation of large pores, affecting the mechanical strength. As the polyol content increased, the matrix exhibited greater fluidity, which enabled it to accommodate more wood flour and penetrate the cell cavity or even the cell wall. This improved infiltration enhanced the interface bonding performance of the composites and made their mechanical properties sensitive to changes in wood flour content. The reprocessing ability of the prepared composites decreased with the increase in wood flour content, and the interface bonding was enhanced after reprocessing. The tensile strength retention rate of the composites prepared with alkali-treated wood flour was lower. This study provides a theoretical basis for optimizing the performance of wood fiber/dynamic polyurethane composites and an exploration path for developing self-healing and recyclable wood–plastic composites, which can be applied to building materials, automotive interiors, furniture manufacturing, and other fields.