High performance bio‐based thermosetting resins composed of tung oil and bismaleimide

The reaction of tung oil (TO) and 1,1′‐(methylenedi‐4,1‐phenylene)bismaleimide (BMI) in 1,3‐dimethyl‐2‐imidazolidinone (DMI) at 150°C for 4 h and subsequent precipitation gave TO/BMI prepolymer, which was cured at 200°C for 2 h gave crosslinked TO/BMI product with CC ratio from 1/1 to 1/4. The FE‐SEM analysis revealed that all the cured products are homogeneous and no phase separation was observed. The glass transition temperature and 5% weight loss temperature of the cured TO/BMI increased with increasing BMI content. The maximal tensile strength (38.1 MPa) and modulus (2.6 GPa) were obtained for the cured products with the CC ratios of 1/2 and 1/3, respectively. To evaluate the reaction of TO and BMI, the model reaction products of TO and N ‐phenylmaleimide (PMI) in DMI were analyzed by 1 H‐NMR spectroscopy. The NMR data of the reaction products of TO/PMI with the CC ratio 2/1, 1/1, 1/2, 1/3, and 1/4 at 150°C for 24 h revealed that Diels‐Alder reaction preferentially occurred at 2/1, and that ene reaction and other reactions such as radical homo and copolymerization gradually increased with decreasing CC ratio of TO/PMI. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011