Preparation and properties of self-healing tung oil-based polymer networks driven by thermo-reversible Diels–Alder reaction.

Mixtures of tung oil (TO) and 4,4'-bismaleimidodiphenylmethane (BMI) in the molar ratios of 1:3 and 2:3 were cured at 100 °C or 160 °C to produce the cured products (TB13, TB23 or htTB13, htTB23). Fourier-transform infrared spectroscopy of the cured products confirmed that the trans, trans-diene moieties of TO are almost completely consumed for all the cured products; furthermore, the maleimide groups were almost completely consumed for all the cured products, except for TB13. Differential scanning calorimetry results of the cured products revealed that TB13 and TB23 exhibited strong endothermic peaks due to the retro-Diels–Alder (rDA) reaction. The rDA enthalpy change (ΔH_rDA) of TB13 was higher than that of TB23, and the ΔH_rDAs of htTB13 and htTB23 were considerably smaller than that of TB13 and TB23. The tan δ peak temperatures of the cured products measured by dynamic mechanical analysis were in the range of 55–131 °C and were increased in the order: TB23 < TB13 < htTB23 < htTB13. The 5% weight loss temperatures of all the cured products were higher than 400 °C. Although TB13 and TB23 exhibited self-healing properties upon hot-pressing at 100 and 120 °C, respectively, htTB13 and htTB23 exhibited no self-healing ability. [ABSTRACT FROM AUTHOR]