Bisphthalonitrile (BAPh) monomer was blended with novolac resins to achieve good processing resin blends. The curing behaviors of the novolac/BAPh (novolac/BAPh) blends were studied by differential scanning calorimetry (DSC) and dynamic rheological analysis. The results indicated that the blends had large processing windows (98-118 degrees C), and they can copolymerize without any other curing additives. The novolac/BAPh copolymers were obtained by short curing times and low curing temperatures. Thermal and thermal-oxidative stabilities of the copolymers were investigated by thermal gravimetric analysis, and the char yields up to 74 and 35% by weight at 800 degrees C were achieved under nitrogen and air atmosphere, respectively. These postcured copolymers exhibited a 5% weight loss temperature of 502 degrees C in air. These results revealed that the copolymers exhibited excellent thermal and thermal-oxidative stabilities. Dynamic mechanical properties of the copolymers were systematically evaluated by dynamic mechanical analysis. The copolymers exhibited higher glass transition temperatures (Tg) as the BAPh content increased. Mechanical properties of the copolymers were investigated, and these data showed that flexural strength and flexural modulus of the 50 : 50 novolac/BAPh copolymers were 91 MPa and 5.78 GPa, respectively. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012