The effect of the resin/hardener ratio on the compressive behavior of an epoxy system

An investigation was carried out on the variation of the mechanical properties of an epoxy system formulated with eight resin/hardener ratios. The ratios used covered a range of epoxy rich and hardener rich, as well as stoichiometric compositions. The tests were performed in compression and the results obtained were correlated with the macromolecular network developed. The epoxy rich systems showed brittle behavior, which was associated with the development of a rigid macromolecular structure. The hardener rich systems showed fracture behavior characteristic of materials with a large deformation capacity. This behavior was associated with the presence of non-reacted points on the hardener molecule and the introduction of a segment with rotational capacity in the macromolecular network. The degree of cure and the number of functional points consumed on the hardener molecule were identified as the two parameters that control the compression behavior of the epoxy system studied.