The relationship between the compatibility and thermodegradation stability of modified polyetherimide/bismaleimide resins by hyperbranched polysiloxane with high degree of branching

Amino‐terminated hyperbranched polysiloxane (AHBSi) with high degree of branching (0.8) is used to improve the compatibilization of polyetherimide (PEI)/allyl bisphenol A modified bismaleimide (BD) blend. The relationship between the compatibility and thermal/thermal‐oxidative stability of the AHBSi/PEI/BD system is intensively investigated. Although PEI has high thermal stability, the PEI/BD blend has poorer thermal stability than BD resin due to the incompatibility. With the addition of AHBSi into the PEI/BD blend, AHBSi chemically connects PEI and BD, leading to the increased compatibility; moreover, interestingly, both thermal and thermo‐oxidative stabilities are significantly improved. Under a N 2 atmosphere, the addition of 0.5 wt% of AHBSi increases the initial degradation temperature of the PEI/BD blend from 395°C to 412°C. The thermodegradation kinetics were studied, and results show that the AHBSi/PEI/BD system has much higher activation energy of degradation in both N 2 and air atmospheres. The origin behind these interesting results is intensively investigated. Copyright © 2013 John Wiley & Sons, Ltd.