Temperature for curing phthalonitrile-terminated poly(phthalazinone ether nitrile) reduced by a mixed curing agent and its curing behavior

A mixture of ammonium molybdate tetrahydrate and urea (AMTU) was developed successfully to catalyze phthalonitrile to afford 2,4,6-tris(2-cyanophenyl)-1,3,5-triazine. Then AMTU was employed as a curing agent to promote the curing reaction of phthalonitrile-terminated poly(phthalazinone ether nitrile) (PPEN-Ph), and the effect of the novel curing agent was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The initial curing temperature and apparent activation energy Ea (based on the Kissinger equation) were reduced from 268.5 degrees C and 201.5 kJ mol(-1) using the common curing agent ZnCl2, to 223.0 degrees C and 78.4 kJ mol(-1) using AMTU, respectively, under identical curing conditions. Moreover, the resulting thermosetting resin over AMTU showed excellent thermal stability; the T-d5% and T-d10% were 487 degrees C and 540 degrees C, respectively, and the char residue was up to 75% at 800 degrees C. These results indicated that AMTU could reduce the curing temperature for PPEN-Ph effectively, and it may be a good candidate as a curing agent for phthalonitrile resins.