2023 Volume 59 Issue 3 Pages 73-80
Epoxy resins with oxazolidone ring （Oxa-E） are expected for structural adhesives because of their good thermal stability. The evaluation of the fatigue crack propagation resistance is required for structural adhesive joints from a viewpoint of long-time reliability and damage tolerance design. The aim of this paper is to investigate the effect of addition of oxazolidone ring into epoxy networks on the fatigue crack propagation properties of the adhesive joint. Epoxy resin with oxazolidone ring was mixed into bisphenol-A diglycidyl ether（DGEBA）． Two types of toughening agents, polyamide particles and core-shell rubber particles, were used. Graphene nanoplatelets were used as sacrifice particles which lead to cohesive fracture. The fatigue crack propagation tests were conducted using tapered double cantilever beam （TDCB） specimens. The optimum content of the graphene nanoplatelets was found to be 0.16wt％ , which shows the cohesive fracture and the highest crack propagation resistance. The adhesive with Oxa-E had the superior fatigue crack propagation resistance to the DGEBA adhesive which has equivalent glass transition temperature and lower molecular weight between crosslinks. On the other hand, it has the similar crack propagation resistance to the DGEBA adhesive which has equivalent molecular weight between crosslinks. These results agreed well with the results of the bulk resin. The adhesive with both heat resistance and long life was achieved by inserting the epoxy with the oxazolidone ring into epoxy network.
