ON THE FORMATION AND PROPERTIES OF A HIGH-TEMPERATURE RESIN FROM A BISPHTHALONITRILE

When 4,4'-bis(3,4-dicyanophenoxy)biphenyl is heated with small amounts of aromatic amine or amidine salts, a highly crosslinked polytriazine is obtained. This polymer has been shown to be the same as that reported when bisphthalonitriles are heated with amines. Salts promote this reaction more readily and the glass transition temperature of the polymer after post-cure at 315-degrees-C is generally 30-degrees-C higher than when free bases are used. The fracture properties and elasticity of the salt-cured polymer have been measured at temperatures up to 250-degrees-C. As a model system, the self reaction of phthalonitrile promoted by amines and their salts has been studied. In both cases, poly[4-(2-cyanophenyl)-1,3,5-triazine-2,6-diyl-1,2-phenylene] is produced, and more efficiently using the salts. A reaction mechanism for this polymerization has been proposed. (C) 1994 John Wiley & Sons, Inc.