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Impact of aliphatic amine comonomers on DGEBA epoxy network properties



This study characterized the mechanical and thermal properties of the oligomer-based formulations of the diglycidyl ether of bisphenol A (DGEBA) cured with series aliphatic amines (triethylenetetramine (TETA), tetraethylenepentamine (TEPA) and O,O bis (2-aminopropyl propylene glycol) (Jeffamine D230) with different functionalities in the glassy state. Impact Izod and three-point bending tests were conducted to determine the networks' impact energy (Ei), elasticity modulus (Ey), yield stress (σy) and fracture toughness (KIC) values. The same three-point bending mode was also employed to characterize the systems' thermo-mechanical properties (DMA) and storage modulus (E') and damping modulus (tan δ = E"/E') values. The DGEBA/D230 network showed greater flexibility, maximum impact energy, higher fracture toughness, and a lower yield stress than the DGEBA/TETA and DGEBA/TEPA networks. The fracture behavior of these epoxy systems was correlated to the molecular weight between the crosslink points, Mc, and the plastic zone size (rp) at the crack tip carved in the samples. The DGEBA/D230 network had the highest storage modulus and tan δ intensity, together with higher toughness and deformation during the network's fracture. These results were a consequence of the structural characteristics of comonomers, including their chain segment flexibility, molecular weight between crosslink points and functionality. POLYM. ENG. SCI., 54:2132–2138, 2014. © 2013 Society of Plastics Engineers