А.N. Blaznov, V.V. Samoilenko, М.Е. Zhurkovsky, V.V. Firsov, N.V. Bychin, Е.V. Atyasova, Z.G. Sakoshev
DOI: 10.25699/SSSB.2020.32.4.004 Download PDF
Abstract: Here we examined an epoxy binder based on the ED-20 resin and the Ethal-M7 hardener of an amine type. This study was aimed at exploring the rheological, physicomechanical and thermomechanical behavior of Ethal-M7-based binder specimens cured at different modes. The initial viscosity of the binder and the viscosity variation were measured on a rotation viscometer as per GOST 25276-82. The glass transition temperature was measured by the TMA technique pursuant to GOST 32618.2-2014; the degree of polymerization and the glass transition were determined by the DSC technique as per GOST R 57687-2017 and GOST R 55135- 2012, respectively. The tensile strength was measured by GOST 11262-2017. The rheological study results for the binder demonstrated that it had an initial viscosity of 2.75 Pa∙s, was low active at room temperature, and could be processed for 2.5 h. The binder had a fairly good tensile strength of 69.5 MPa after 4-h curing at 60 °С, keeping up with other composites in the same class. The TMA analysis showed that the binder based on curing agent Ethal-M7 had two glass transitions: the first one was basic, ranging from 52 to 66 °С, and the second one was between 83 and 108 °С. The glass transition temperature after 3-day curing at room temperature ranged from 56 to 62 °С, and after 12 days, from 53 to 66 °С. Following 2-h curing at 23 °С and then 4-h curing at 60 °С, the temperature transition increased to 73–80 °С; the second peak did not show up. The DSC analysis of the binder cured in the mode of 2 h at 23 °С + 4 h at 60 °С demonstrated that the first endoeffect corresponded to the glass transition temperature of 79.8 °С, while the second endoeffect at 120.3 °С pertained to the second glass transition temperature.
Index terms: epoxy binders, amine hardener, Ethal-М7, Ethal-45М, Ethal-23Х, TMA, DSC, strength, tension, glass transition temperature, curing, degree of polymerization.


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