Cure kinetics and thermal properties of novel bismaleimide containing phthalide cardo structure

A novel bismaleimide containing phthalide cardo structure (BMIP) was mixed with 2,2′-diallyl bisphenol A (DABPA), and the cure behavior of the mixture was studied by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The FTIR results demonstrated the cure reaction below 200 °C progressed preferentially via alternating copolymerization of maleimide and allyl groups. The DSC thermogram of the prepolymer showed three different cure regimes in the temperature range of 100–350 °C and the 2nd exothermic peak was predominant. The kinetic parameters of the 2nd curing process were evaluated using various kinetic models: Kissinger and Ozawa–Flynn–Wall, and the apparent activation energies obtained from two methods were consistent with each other. Thermal properties of the cured network were characterized by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Experimental results exhibited that the onset decomposition temperature (T5%) was ∼431 °C and char yield at 600 °C was ∼39.1%. In addition, the glass-transition temperature (Tg) reached 274 °C based on the tan δ peak temperature.