Continuous protective layer derived from organic-inorganic hybrid particles: An effective method for thermal degradation resistance and mechanical performance of phthalonitrile composites

In order to meet the aerospace applications, a series organic-inorganic hybrid particles (PEB1-3) were prepared by coating polyetherketone-cardo (PEK-C) on the boron powders to improve the thermal degradation resistance of phthalonitrile (PN). A continuous protective layer derived from hybrid particles can form at high temperatures, effectively isolating heat and oxygen. After adding 22.5 wt% PEB2, the temperature of 5 % mass loss (T_5%) of PN hybrid resin (PN-PEB2) was significantly delayed from 485 °C to 535 °C. PEB2 exhibited outstanding heat-resistant modification efficiency in PN matrix. In a series of thermal degradation experiments, the surface morphology of PN-PEB2 was mostly maintained after thermal degradation at decomposition temperature. For PN-PEB2 composite, the flexural strength (FS) and interlaminar shear strength (ILSS) were increased by 40.4 % and 44.8 % compared with the PN composite, respectively. After thermal degradation at 350 °C for 100 h, the FS retention rate of PN-PEB2 composite was 67.1 %.