Study on the deformation and fracture of epoxy monoliths through mechanical tensile and compressive tests and X-ray CT imaging

Abstract

As porous polymer materials with continuous epoxy skeletons and pores, epoxy monoliths are used as column fillers in HPLC, separators in lithium-ion batteries, and precursor polymers for monolith adhesion and co-continuous network polymer fabrication. Due to their unique mechanical properties and fracture behavior, epoxy monoliths can incur large deformation and are different from the bulk thermoset of epoxy resins that exhibit hard and brittle features. In this study, we prepared an epoxy monolith using 2,2’-bis(4’-glycidyloxaphenyl)propane (BADGE) and tripropylene glycol diglycidyl ether (TPGD) as epoxy resins, 4,4’-methylenebis(cyclohexylamine) (BACM) as a crosslinker, and poly(ethylene glycol) (PEG) as a porogen, and TPGD-induced effects on the pore structure and properties of the obtained monoliths were investigated. To clarify the relationship between the pore structure and the mechanical properties of the monolith, scanning electron microscopy (SEM) observations and tensile and compression tests were performed. In addition, X-ray CT imaging nondestructively revealed a change in the inner porous structure of the monolith after a large deformation occurred under various compression conditions. We clarified the effects of the TPGD addition on the monolith structure and the mechanical properties with tensile and compressive deformation. As porous polymer materials with continuous epoxy skeletons and pores, epoxy monoliths exhibit unique mechanical properties and fracture behavior different from the bulk thermoset of epoxy resins. In this article, we describe the thermal properties, pore structures, and mechanical properties of epoxy resins with tensile and compressive deformation of the monoliths. In addition, a change in the inner porous structure after large deformation was nondestructively observed by X-ray CT imaging.