Copolymerization modification: improving the processability and thermal properties of phthalonitrile resins with novel comonomers

Two novel tetrahydrophthalic anhydride end-capped imide compounds (THAN and THBN) with high thermal stability were synthesized to promote the curing reaction of 1,3-bis(3,4-dicyanophenoxy)benzene (3BOCN), and to study the effects of comonomer structure on the curing behavior and thermal performance of phthalonitrile resins. The curing behaviors of THAN/3BOCN and THBN/3BOCN blends with various molar ratios were investigated using rheological analysis and differential scanning calorimetry, suggesting a wide processing window. Dynamic mechanical analysis and thermogravimetric analysis showed that the cured resins possessed high glass transition temperatures (> 500 °C), and superior thermal and long-term thermo-oxidative stabilities with weight retention of 95% ranging from about 544 to 558 °C in both nitrogen and air. All these results indicated that the processability and thermal properties of phthalonitrile resins could be improved further by modifying the structure of comonomer in this kind of curing system. © 2018 Society of Chemical Industry