Synthesis and characterization of multifunctional propenyl-endcapped aromatic co-monomers and their use as bismaleimide modifiers

A series of novel modifiers for bismaleimide, bearing propenyl and phenoxy functional groups has been synthesized. Structural information of the monomers was obtained through Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. Polymerization characteristics demonstrate that all four systems prepared have a cure temperature below 210°C. This remarkably lower cure temperature compared to that of other polymerization reactions involving diallyl bisphenol A and bismaleimide (DBMI) originates from propenyl groups being present in the structures as well as their larger free volume. The rheological behaviors leading to low melt viscosities and the wide process window of the prepolymer are particularly suitable characteristics for the production of performance resin-based composite materials via resin transfer molding processes. The dynamic mechanical analysis of the materials reveals glass transition temperatures in a range between 260°C and 293°C. Thermal stabilities show a 5% weight loss at temperatures ranging from 363°C to 428°C with the production of char ranging from 38.5% to 57.6% at 800°C under nitrogen. The latter is a clear indication for the excellent thermal stabilities featured by the cured resins. Furthermore, the dielectric properties exhibit a significantly lower dielectric constant and dissipation factors of the propenyl-modified cured systems compared to those of DBMI resins at 10 GHz. Copyright © 2015 John Wiley & Sons, Ltd.