1Department of Chemistry, Malek Ashtar University of Technology, Tehran, I.R. IRAN
2Space Transportation Research Institute, Iranian Space Research Center, Tehran, I.R. IRAN
Polysulfide resins,with trade name of G4 and G112, with short and long chain lengths respectively, were used as reactive modifiers to toughen epoxy resin. The effects of molecular weights of G4 and G112 on impact resistance, dielectric constant, thermal conductivity as well as decomposition heat and adhesion properties of toughened epoxy were investigated. The impact strength and the dielectric constant of epoxy resin were enhanced by increasing of polysulfide so that the effect of the G112 is higher than the G4. For the same weight percent of G4 and G112, the G112 modified epoxy resin has lower Cure enthalpy than the G4 modified epoxy resin. Addition of modifier with long chain up to 10 weight percent was also leaded to higher bond strength with aluminum sheets. also, It is observed that the thermal conductivity of epoxy decreasing with incresing modifier chain length.