A quantitative approach to dynamic and isothermal curing of an epoxy resin modified with oligomeric siloxanes

Abstract

The reactivity of a system comprising commercial epoxy resin Epidian® 6 (E6) and triethylenetetramine (Z-1) hardener was studied. The system was modified with two low-molecular siloxane modifiers: 1,3-bis(glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane (DS1) and 1,3-bis(aminopropyl)-1,1,3,3-tetramethyldisiloxane (DS2). The modifiers replaced 10 mass% of E6 or Z-1, respectively. The systems E6/DS2 and DS1/Z-1 were also studied. Enthalpy of curing was determined for all systems in isothermal conditions and dynamically, i.e., in the range of 0-250 °C with linearly increasing temperature at the rate of 2, 5, 10, and 20 °C min-1. The activation energy of curing was determined using isoconversional methods by Friedman and Kissinger-Akahira-Sunose. The epoxy systems containing siloxane modifiers had generally lower activation energies than the reference E6/Z-1 system. The time to gelation measurements were taken using the temperature-modulated differential scanning calorimetry.