Abstract: The toughening of epoxy resin (EP) with amino silicone oil (AS) was studied. Chemical structure and thermal stability of cured EP with or without AS was compared. In a preferred process, 6 % AS was introduced into EP, stirred for 1 h at 50 °C, after cooled down to room temperature, a curing agent was added and cast to a film and cured for 24 h at room temperature. Thus obtained film gave rise to the optimal comprehensive properties: impact strength was 41 kg.cm, the adhesion strength was 6.800 MPa，he initial decomposition temperature of the EP skeleton in the air was 332.1 °C. During the curing process, AS was bonded with EP in the form of the C-N-C bond because the primary amine of AS reacted with the epoxy groups of EP to generate a secondary amine.

Key words: epoxy resin, amino silicone oil, modification, impact strength, thermal stability