Comparative study of the kinetic behaviors and properties of aromatic and aliphatic bismaleimides

In this paper, three aromatic bismaleimides (BMI-70, BMI-DE and BMI-80) and two aliphatic bismaleimides (BMI-DDA and BMI-C36) were synthesized. The structures were characterized using nuclear magnetic resonance (NMR) spectra and Fourier transform infrared (FT-IR) spectra. Their polymerization behaviors were discussed by non-isothermal differential scanning calorimetry (DSC). The thermal and dielectric properties of the poly(bismaleimide) were investigated using thermogravimetric analysis (TGA), dynamic thermo-mechanical analysis (DMA), and an impedance analyzer. The results indicate that the aliphatic bismaleimides exhibit lower apparent activation energies and dielectric properties, with BMI-DDA displaying an average activation energy of 105.5 kJ mol⁻¹ and the dielectric constant of P(BMI-C36) is 2.558 @ 10 MHz. The aromatic polybismaleimides possessed better thermal stability, among which, the 5 % thermal decomposition temperature (T_d,5) of P(BMI-70) was 513.5 °C, and the residual carbon rate at 800 °C was 44.6 %. In additional, water absorption was studied and their saturated water absorption was less than 4 %.