The fatigue behavior of structural adhesives composed of a bisphenol type epoxide resin, aliphatic α, ω dicarboxylic acids HOOC-(CH2)p-COOH (p=2, 4, 8, 10), an amine-type accelerator and an amine-type catalyst was investigated by analyzing the results of fatigue tests, bulk properties and SEM of fractured surfaces of the systems. Ether type, ester type and the mixed type network structures were formed by using the amine catalyst and the carboxylic acids with and without accelerator.
On the basis of the above observations, the mechanism for improvement of fatigue strength was discussed in terms of the segmental structures, high relaxational ability, transformation of mechanical stress into heat, and restricted segmental motion for the cured systems.
A good correlation of the fatigue strength with the concentration of network chains, fracture energy or area of tanδ curve was found.
