Thermal-oxidative aging mechanism of carbon fiber reinforced self-catalytic phthalonitrile resin matrix composite laminates at 450 ℃ ∼ 500 ℃

For advancing heat-resistant of carbon fiber reinforced phthalonitrile composites as load-bearing materials, a kind of self-catalytic phthalonitrile resin serving at 450 ℃ ∼ 500 ℃ has been developed and was used to fabricate carbon fiber reinforced phthalonitrile composite laminates. Combined with pyrolysis kinetic equation, mass loss rate and micromechanical behaviors, this paper systematically investigated thermal-oxidative aging mechanism of composite laminates at 450 ℃ and 500 ℃ from three components: phthalonitrile resin, carbon fiber and interface. The pyrolysis mechanism of phthalonitrile resin was explored by a combination of thermogravimetric analysis and pyrolysis–gas chromatography-mass spectrometry. The results illustrate that phthalonitrile resin possesses good thermal stability with the formation of aromatic heterocyclic structures. The pyrolysis kinetic model of phthalonitrile resin at 450 ℃ ∼ 500 ℃ is attributed to two-dimensional diffusion mechanism. The thermal-oxidative aging behavior of composite laminates strongly depends on pyrolysis of phthalonitrile resin and the degradation of interface. Compared with the properties of composite laminate at room temperature, high retention rates of flexural property and interlaminar shear strength under elevated temperatures are obtained after 450 and 500 °C thermal-oxidative aging. It suggests the great potential of phthalonitrile composites to be used as light-weight load-bearing materials serving at 450 °C ∼ 500 °C.