Correlation between nodular morphology and fracture properties of cured epoxy resins

摘要: Various bulk epoxy resin formulations, based on diglycidyl ether of bisphenol A (DGEBA) and cured with diethylene triamine (DETA) were studied. Methods linear elastic fracture mechanics employed all systems characterized by the corresponding values critical strain energy release rate for crack initiation arrest. Fracture morphology was studied scanning electron microscopy transmission carbon—platinum surface replicas. An apparent correlation between ultimate mechanical properties has been found. All surfaces are shown to be distinct nodular morphology. Nodules, ranging in size from 15–45 nm, represent sites higher crosslink density an inhomogeneous network structure. further three propagation zones. smooth, brittle zone preceded followed arrest zones, respectively. plastic flow confined regions. No crazing phenomenon seen zone; instead a step-like observed, typified ‘flow’ internodular matrix during step formation. Local deformation value rate, GIc, correlated The nodules found vary curing agent concentration, thus allowing us establish fundamental resins.