PHTHALONITRILE CURE REACTION WITH AROMATIC DIAMINES

Phthalonitrile monomers can be polymerized thermally in the presence o f small amounts of curing agents into thermosetting polymers. The ther mosets exhibit outstanding thermo-oxidative stability, display good me chanical properties, and offer promise as matrices for composite appli cations. The phthalonitrile cure reaction is typically accomplished wi th an aromatic diamine, 1,3-bis(8-aminophenoxy) benzene (m-APB), added in the range of 1.5-2% by weight of the monomer in the melt phase. Th is article addresses the cure reaction with a sulfone-containing diami ne, bis[4-(4-aminophenoxy)phenyl] sulfone (p -BAPS), which shows lower volatility as determined from thermogravimetric studies (TGA) compare d to m-APB at the processing temperatures typically employed for phtha lonitrile cures. Rheometric studies conducted to monitor the viscosity increase during a cure reaction suggest that the cure reaction with m -APB is faster compared to the reaction with B-BAPS. Even though diffe rences are seen in the initial cure rates, the final cured products ar e similar in terms of the glass transition temperatures and thermal an d oxidative stabilities. (C) 1998 John Wiley & Sons, Inc.