A highly efficient, organic solvent-free biorefinery strategy for high-purity Eucommia ulmoides gum extraction and its etherified lignin-modified composites

An organic solvent-free biorefinery process was developed for the efficient extraction of high-purity Eucommia ulmoides gum (EUG) from seed shells by integrating alkaline pretreatment, disk milling, and air flotation purification. Under optimal conditions (5 % NaOH, 100 °C, 1 h of air flotation), EUG with a purity of 98.2 % and a yield of 22.2 % was obtained, eliminating the need for hazardous organic solvents. Structural analyses (FT-IR NMR, XRD) confirmed the extracted products as trans -1,4-polyisoprene. Furthermore, etherified lignin (ESL) was incorporated into EUG to fabricate composite films. The resulting ESL/EUG composites exhibited tunable mechanical properties, enhanced UV-aging resistance, increased hardness, and improved shape memory performance. Notably, the ESL/EUG composite containing 5 wt% ESL achieved a high shape recovery ratio of 94 %, demonstrating potential for applications in orthopedic braces and sports protective equipment. This work presents a highly efficient, eco-friendly sustainable approach for the integrated valorization of Eucommia ulmoides Oliver (EUO) resources into high-value bio-based materials. • An organic solvent-free process for high-purity EUG extraction was developed. • EUG product with high purity (98.2 %) and high yield (22.2 %) was obtained. • ESL/EUG composites with excellent UV-aging resistance were fabricated. • The 5 wt% ESL/EUG composite showed superior shape memory (94 % recovery ratio).