Nitrile functionalized Al₂O₃ reinforced polyarylene ether nitriles terminated with phthalonitrile composites

Nitrile functionalized Al₂O₃ (Al₂O₃-CN) particles were employed to reinforce polyarylene ether nitriles terminated with phthalonitrile (PEN-t-CN) polymer. The composites were prepared via hot pressure casting technique in the form of a sheet. To improve the interfacial compatibility between polymer matrix and Al₂O₃, Al₂O₃ was nitrile functionalized by bisphthalonitrile (BPH) previously and confirmed by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA). The micromorphology, thermal, mechanical and dielectric properties of Al₂O₃-CN/PEN-t-CN composites were systematically investigated. The Al₂O₃/PEN-t-CN composite with 5 wt% raw Al₂O₃ was prepared for comparison. SEM observations indicated that the Al₂O₃-CN particles exhibited rough surface which resulted in favorable interfacial compatibility with PEN-t-CN polymer matrix. DSC curves revealed that the glass transition temperature (T _g ) of the Al₂O₃-CN/PEN-t-CN composites were in the range of 178 to 185 °C, indicating that all the composites exhibited high working temperature. The results of TGA indicated that the Al₂O₃-CN/PEN-t-CN composites showed excellent thermal stabilities with initial degradation temperature (T _id ) up to 491 °C in N₂ atmosphere. The tensile strength increased from 93.51 MPa for Al₂O₃/PEN-t-CN composite to 97.91 MPa for Al₂O₃-CN/PEN-t-CN composite with 15 wt% Al₂O₃-CN loading. It was also observed that the dielectric constant of composites increased regularly with increasing the content of Al₂O₃-CN and the dielectric loss exhibited little dependence on frequency. In sum, excellent mechanical properties combined with good operating temperature of the Al₂O₃-CN/PEN-t-CN composites would lead to particularly attractive for practical applications in aerospace, automotive, and industrial fields.