Curing Mechanism, Thermal Properties, and Adhesion Properties of Propenyl- and Allyl- Endcapped Aromatic Monomer/Bismaleimide Systems
Six compounds for bismaleimide (BMI), containing propenyl and allyl groups in the molecular structures, were synthesized via the nucleophilic substitution routes. Polymerization mechanism and behaviors of the propenyl-endcapped monomers with BMI were studied by FTIR and differential scanning calorimetry (DSC). The remarkable lower cure temperatures (171-230 °C), compared with that of the normal reactions of the diallyl bisphenol A/bismaleimide (DBMI) (approx. 270 °C), are mainly caused by the electron-donating propenyl groups and the multifunctional structures. The dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA) of the cured resins showed the high glass transition temperatures (Tgs). Thermogravimetric analysis (TGA) with 5% weight loss temperatures ranging from 363 °C to 437 °C reveal that the cured resins have the better thermal stabilities than that of the commercial DBMI system. The dielectric properties were measured by a dielectric spectra detector, which exhibit the lower dielectric constant (2.98-3.25) and dissipation factors (0.002-0.01) of the propenyl-modified cured systems compared with that of the DBMI resin (3.43, 0.012) at 10 GHz. In addition, the lap shear strengths of the propenyl-modified system were higher than that of DBMI samples especially at high temperature.
Authors: Changwei Liu, Chunyan Qu, Wanbao Xiao, and Dezhi Wang
Conference: SAMPE Seattle 2017