To find a proper amine to promote the processability of phthalonitrile-based composites, three different aromatic amines: 4-aminophenoxyphthalonitrile (APN), 2,6-bis (4-diaminobenzoxy) benzonitrile (BDB) and 4,4'-diaminediphenyl sulfone (DDS) were used as curing agents to investigate the crosslinking behavior and thermal decomposition behavior of phthalonitrile oligomer containing biphenyl ethernitrile (2PEN-BPh). Differential scanning calorimeter (DSC) and dynamic rheological analysis were employed to study the curing reaction behavior of the phthalonitrile/amine blends and prepolymers. The studies revealed that BDB was the preferred curing agent and the preferred concentration of BDB was 3 wt %. The thermal properties of the 2PEN-BPh polymers were monitored by TGA, and the results indicated that all the completely cured 2PEN-BPh polymers maintained good structure integrity upon heating to elevated temperatures and these polymers could thermal stabilize up to over 550 degrees C in both air and nitrogen atmospheres. Dynamic mechanical analysis (DMA) showed the glass transition temperature (T-g) exceeded 450 degrees C when the 2PEN-BPh polymer post cured at 375 degrees C for 8 h. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 2331-2337, 2011