Effect of lignin on the structure-property behavior of metal-coordinated and chemically crosslinked ethylene-propylene-diene-monomer composites.

The efficient development and utilization of green biomass-based macromolecule engineering materials are essential for the sustainable development of human civilization. In this study, lignin-based ethylene-propylene-diene-monomer (EPDM) composites with excellent mechanical performance were fabricated using a simple method. The effects of water-insoluble enzymatically hydrolyzed lignin (EL) and alkali lignin (KL) on the mechanical performance of the composites were investigated separately. The results showed that the tensile strength of EPDM reinforced with KL and EL increased to 24.5 MPa and 22.1 MPa, respectively, surpassing that of the carbon black (CB)-reinforced EPDM. After 72 h of thermo-oxidative aging, the retention rates of the tensile strength and elongation at break in the lignin-reinforced EPDM were much better than those formed with pure CB, indicating that lignin significantly improved the thermo-oxidative aging resistance of the composites. In summary, the Zn2+ coordination bonds formed between the interface of EPDM and lignin in lignin/CB/EPDM ternary composites effectively improved the mechanical performance and aging resistance of the composites. This study has significant implications for enhancing the utilization of lignin and green functional polymer materials.

Novel Lignin-Functionalized Waterborne Epoxy Composite Coatings with Excellent Anti-Aging, UV Resistance, and Interfacial Anti-Corrosion Performance.

Developing high-performance lignin anti-corrosive waterborne epoxy (WEP) coatings is conducive to the advancement of environmentally friendly coatings and the value-added utilization of lignin. In this work, a functionalized biomass waterborne epoxy composite coating is prepared using quaternized sodium lignosulfonate (QLS) as a functional nanofiller for mild carbon steel protection. The results showed that QLS has excellent dispersion and interface compatibility within WEP, and its abundant phenolic hydroxyl, sulfonate, quaternary ammonium groups, and nanoparticle structure endowed the coating with excellent corrosion inhibition and superior barrier properties. The corrosion inhibition efficiency of 100 mg L-1 QLS in carbon steel immersed in a 3.5 wt% NaCl solution reached 95.76%. Furthermore, the coating maintained an impedance modulus of 2.29 × 106  Ω cm2 (|Z|0.01 Hz ) after being immersed for 51 days in the high-salt system. In addition, QLS imparted UV-blocking properties and thermal-oxygen aging resistance to the coating, as evidenced by a |Z|0.01 Hz of 1.04 × 107  Ω cm2 after seven days of UV aging while still maintaining a similar magnitude as before aging. The green lignin/WEP functional coatings effectively withstand the challenging outdoor environment characterized by high salt concentration and intense UV radiation, thereby demonstrating promising prospects for application in metal protection.