Thermal, mechanical and dielectric property enhancement of benzoxazine-containing phthalonitrile resin: The effect of functional oligomeric polyphenyl ether

Two oligomeric polyphenyl ethers (PPE) with different functional groups (hydroxyl group and allyl group) were introduced into the benzoxazine-containing phthalonitrile resin, in order to improve the dielectric properties. The polymerization mechanism of the two systems was investigated in detail and the comprehensive properties were studied. It was found that both hydroxyl-terminated PPE (PH) and allyl-terminated PPE (PA) could effectively promote the curing of phthalonitrile resin, while the PH system showed higher activity. Nevertheless, PH could not polymerize and chemically bonded with the crosslinking network. While the allyl groups in PA, however, could self-polymerize or copolymerize with phthalonitrile resin and the thermal resistance and dimensional stability improved as a consequence. PA system shows better dielectric properties, due to the low polarity of functional groups. Poly(MBP-30PA) showed the lowest dielectric constant of 2.88 at 1 MHz. Additionally, the mechanical strength of the glass fiber reinforced composites was also improved. G(MBP-20PA) showed flexural strength of 561.8 MPa, 155.1 MPa higher than that of G(MBP).