Enhanced Modification of Fast-Growing Wood: Application and Evaluation of Castor Oil-Based Unsaturated Polyester Resin

[Image: see text] A type of multifunctional maleic acid ester monomer (COEGMA) was synthesized using castor oil as raw material, and green wood–plastic composites were prepared by chemically impregnating and curing the monomer into wood. The structure of the synthesized products at various stages was determined by FT-IR spectroscopy, (1)H NMR, and GPC, and the curing experimental conditions were optimized. The results show that the water absorption of wood–plastic composites treated with COEGMA is reduced from the original 167.3% to less than 20%. The compressive strength has increased from 35.7 to 86.1 MPa, and the thermal stability has also increased by 40 °C. This research provides promising prospects for the development of environmentally friendly wood–plastic composites, especially as fossil resources become scarce and environmental pollution becomes more severe.