Synthesis of bio-based epoxy resins derived from itaconic acid and application in rubber wood surface coating

Epoxy resin (E51) is commonly used due to its robust strength and high modulus, but its embrittlement is caused by its high cross-link density, which limits its use in many applications. In this research, the itaconic-based epoxy (EIA/E51) with “flexible” and “rigid” cooperative structures has been developed, and a simple strategy has been proposed to build functional epoxy coatings on rubber wood surfaces. The results showed that EIA has low viscosity and molecular weight, it can act as a diluent to reduce the viscosity of E51 from 10 to 16 Pa·s to 0.27 Pa·s for better processibility. The EIA/E51 thermosets exhibited good thermal and mechanical properties, and the single glass transition temperature (Tg) proved to be the homogeneous phase structure of the EIA/E51/DDM thermosets. When EIA was incorporated into E51, the 0.25EIA/0.75E51/DDM exhibited a high Tg (130.9°C). The toughness, impact strength and the elongation at break of 0.50EIA/0.50E51/DDM increased by 203.8 %, 49.7 % and 154.6 %, compared with pure E51. SEM confirmed the morphology of EIA/E51/DDM exhibiting the ductile fracture. Moreover, the itaconic-based epoxy coatings were suitable for use in rubber wood, and the rubber wood coatings have excellent hardness, adhesion, water resistance, and solvent resistance, which protect the rubber wood against moisture conditions. Therefore, this work provides a potential alternative to commercial epoxy resins and reinforces the toughness of E51. This research also extends the application of rubber wood in the industry. [Display omitted] •EIA with low viscosity was synthesized from the sustainable itaconic acid.•EIA is an effective diluent can improve the processibility of E51.•0.50EIA/0.50E51/DDM showed outstanding impact strength.•The epoxy coatings of rubber wood presented excellent physical properties.