Low temperature fracture toughness of polysulfide modified BPA-epoxide primers

Abstract A mixture of amidoamine and polysulfide crosslinkers were used to toughen a BPA-epoxide primer. Viscoelastic properties, fracture toughness, impact resistance, adhesion strength, corrosion properties were investigated. Fracture toughness study was conducted at ambient and low temperatures to approximate an aircraft at altitude. At ambient temperature, the amidoamine was sufficiently flexible due to ethylene oxide soft segments. However, at low temperature, the addition of polysulfide showed improved fracture toughness. The SEM of fractured surface revealed that fracture toughness improvement at low temperature is due to the both cavitation and shear yielding of polysulfide domains and epoxide matrix which dissipate energy and increase the toughness.