Epoxy adhesives are generally more resistant to a wide variety of liquid environments than other structural adhesives. However, they are generally considered to be very rigid systems, and as such they do not have exceptionally good impact or peel resistance unless modified with tougheners.
RESULTING PROPERTIES
The above table presents typical three component epoxy adhesive formulations using polybutadiene with maleic anhydride as a toughening agent. The material is mixed 2:1 Part A : Part B by weight and then the DAMA 1010 is mixed into the formulation. This epoxy system is claimed to provide a hydrophobic backbone, low viscosity, softness and high tensile strength and adhesion. Typical cured properties are:
Hardness
75 Shore D
Tensile Strength
2650 psi
Lap Shear Strength
9350 psi
Tg
119°-127°C
This adhesive formulation can cure at either room temperature or elevated temperatures. Tensile shear strength and temperature resistance of these adhesives are relatively high. Peel strength is also high and does not decrease rapidly with lower temperatures. The durability of polybutadiene modified epoxies is satisfactory as measured by most long term moisture tests.
