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Keywords:

  • renewable resources;
  • thermosets;
  • Diels-Alder polymers;
  • tung oil;
  • bismaleimide

Abstract

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 C[DOUBLE BOND]C 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 C[DOUBLE BOND]C 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 1H-NMR spectroscopy. The NMR data of the reaction products of TO/PMI with the C[DOUBLE BOND]C 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 C[DOUBLE BOND]C ratio of TO/PMI. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011