Novel Bismaleimide Resins Modified by Allyl Compound Containing Liquid Crystalline Structure

A novel allyl compound containing liquid crystalline structure, i.e., 4,4’‐bis(4‐allyloxy benzoic acid) phenyl ester (BAOBE), was synthesized. The chemical structure of BAOBE was characterized by Fourier transform infrared (FTIR) spectroscopy and 1 H NMR spectra, and the liquid crystalline properties were confirmed by polarized optical microscopy (POM). Besides, a series of modified bismaleimide (BMI) resins were prepared based on N , N ′‐4,4′‐bismaleimidodiphenylmethylene (BDM), BAOBE, and O,O ’‐diallyl bisphenol A (DABPA). The results of thermogravimetric analysis (TGA) indicate that the modified resins have excellent thermal stability with the highest temperatures for 5% weight loss above 438°C. The results of dynamic mechanical analysis (DMA) suggest that the glass transition temperature ( T g ) of the modified resins are above 280°C. Besides, the introduction of BAOBE leads to a significant improvement in the flexural and impact properties of the modified BMI resins. Compared with the resin with only DABPA as a modifier, the highest flexural and impact strength can reach 156.2 MPa and 15.6 kJ/m 2 , increased by 19.2% and 90.2%, respectively.