Fatigue behaviors of structural adhesives composed of epoxide resin and aliphatic α, ω-dicarboxylic acids HOOC-(CH2)p-COOH (p=2, 4, 8 or 10) were investigated by analyzing the results of fatigue test and bulk properties of the systems.
The fatigue strength and maximum value of damping increased with increasing p. The glass transition temperature, tensile strength, shear adhesive strength by tension, shear modulus and crosslinking density decreased with increasing p.
On the basis of the above observations, improvement of fatigue strength was explained by considering low restriction of segmental motions, high relaxational ability, transformation of mechanical stress to heat and flexible structure of the cured system.
A good correlation of fatigue strength with crosslinking density or area of tan δ curve was found to exist.
