2. Experimental
2.1. Materials
Tung oil was obtained from the Institute of Chemical Industry of Forestry Products (Nanjing, China). Epichlorohydrin (99%), sodium hydroxide (97+%), maleic anhydride (99%), benzyltriethylammonium chloride (97%), acetone (99%) and 2-ethyl-4-methylimidazole (99+%) were obtained from Sigma–Aldrich (St. louis, MO, USA) and used as received.