Toughening effect of self-assembled thermoplastic particles on phthalonitrile containing benzoxazine and improved mechanical properties in the presence of fibers reinforcement

Phthalonitrile containing benzoxazine resin (BA-ph) was a new type of high-performance resin which could be used at high temperature by autocatalytic molding at low temperature. However, its brittleness after polymerization and weak interaction with fibers when it as the matrix of fiber reinforced composites (FRC) were obstacles to its wide application. In this study, Poly (arylene ether nitrile) containing phenolphthalein (PP-PEN) was introduced by solution blending to toughen BA-ph and its glass fiber (GF) FRC. The effects of PP-PEN on the crosslinking behavior and processability of BA-ph were studied by differential scanning calorimetry (DSC) and dynamic rheology analysis (DRA). The effect of PP-PEN on the structural strength and thermal stability of BA-ph/GF was further studied by other characterization methods. The non-notchable impact strength of BA-ph/PP-PEN/GF FRC formed at lower temperature (200 °C) could reach 148 kJ/m2, which was 91.4% higher than that of BA-ph/GF FRC. Furthermore, the fracture morphology showed that PP-PEN significantly enhanced the interfacial strength between BA-ph and GF. It has potential applications in aerospace, rail transportation and the fields requiring high-performance polymer matrix FRC.