Research on Thermal Aging Properties of Modified E-51 Epoxy Resin for Power-on Warning Helmet

Abstract

Abstract The power-on warning helmet was used to detect the three- dimensional electrical field near electrical equipment with high voltage. However, the power-on warning helmet will be used in low temperature (-40℃) and high temperature (50℃) environment, E-51 epoxy resin with medium viscosity will be chosen to insulate the joint of conducting wire and fill the seam between two neighboring insulating plates of housing shell. Due to brittleness, the unmodified E-51 epoxy resin system can’t absorb huge internal stress at cryogenic temperature, so the modified E-51 epoxy resin system was developed to investigate the thermal aging properties, which aims at revealing the influence of heating temperature and heating time on the evolution of micro structure, thermo stability of micro structure and mechanical properties. The testing results indicate the micro structure of modified E-51 epoxy resin system is stable after 50 thermal cycling, and the micro structure of modified E-51 epoxy resin system is stable after 50 thermal cycling & heating 105 ℃ & 120 h too. Compared with the mechanical tensile strength of modified E-51 epoxy resin system after 50 thermal cycling & heating 105 ℃ & 120 h, the mechanical tensile strength of modified E-51 epoxy resin system after 50 thermal cycling & heating 105 ℃ & 240 h declines about 13.63%. However, the modified E-51 epoxy resin system after heating for 480 h can lead to significant change of micro structure. The mechanical tensile tests indicate the defects in cured system can lead to dramatically decrease of tensile strength. Consequently, in order to obtain high performance, modification and micro homogeneity of E-51 epoxy resin system are necessary.