Novel benzimidazole-mediated phthalonitrile/epoxy binary blends system with synergistic curing behavior and outstanding thermal properties

Binary blends composed of benzimidazole-containing phthalonitrile (PNBI) and epoxy resin E51 were prepared. The PNBI/E51 (PE) blends showed good compatibilities and unique synergistic curing behaviors on full consumption of nitrile groups (PE19, PNBI: E51 = 1 : 9 in weight ratio) and epoxy groups in the view of DSC, rheology and IR. Curing procedures of the PE blends were determined by DSC and DMA. Studies on the curing procedure showed that the PE blends exhibited good processability and could be fully cured at a temperature lower than 210 degrees C. Studies on the cured PE blends showed that they have excellent thermal and mechanical properties. The glass transition temperatures (T-g) of cured PNBI/E51 blends were higher than 207 degrees C (obtained by DMA). The 5% weight loss (T-5) and char yield at 800 degrees C (CR) were higher than 360 degrees C and 14% in nitrogen, respectively (obtained by TGA). Consequently, this study shows a novel modification in the method for the preparation of epoxy or phthalonitrile blend systems.