Toughening Mechanism of Polyetheramine-Modified Epoxy Resins

In this research polyetheramine (PEA)-modified epoxy was prepared and the toughening mechanism of the modified networks was studied. According to the mechanical test results, incorporation of PEA into epoxy networks can significantly toughen the epoxy matrix. The addition of 15 phr PEA increased the critical stress intensity factor (K_IC) and critical strain energy release rate (G_IC) of the epoxy from 0.85 MPa.m^1/2 to 1.86 MPa.m^1/2 and from 0.38 kJ.m⁻² to 2.27 kJ.m⁻², respectively. The toughening and failure mechanisms were discussed based on microscopy of the crack tips. As a result, shear yielding as a possible toughening mechanism was proposed based on microscopical investigations. These in-depth studies could uncover underlying structure-property relationships in a relevant class of PEA-like modifiers, shedding light on the future design of top-performing homogeneous tough polymer networks.