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Curing behaviour and thermal properties of epoxy resin cured by aromatic diamine with carborane

A new kind of carborane-containing aromatic diamine, 1,2-bis (4-aminophenyl)-1,2-dicarba-closo-dodecaborane (HPPA), as a curing agent for epoxy resins was synthesized and confirmed by proton, carbon and boron nuclear magnetic resonance imaging, Fourier transform infrared spectroscopy and elemental analysis. The compatibility, thermal curing behaviour and thermal properties of HPPA/epoxy resin E51 system were investigated. HPPA exhibited good compatibility with E51. Compared with 4,4′-diaminodiphenylsulphone (DDS)/E51, HPPA/E51 system had higher reaction activity and lower curing temperature. When the ratio of amine protons versus epoxy groups was 1:1 in resin systems, the epoxy resin cured by HPPA exhibited the highest glass transition temperature of 207°C. The residual weight ratios of cured HPPA/E51 at 800°C under argon and in air atmospheres were 43.7% and 50.5%, respectively, which were 28.6% and 47.2% higher than that of DDS/E51, respectively, indicating that the HPPA/E51 system had good heat resistance.