Effects of Accelerated Climatic Aging on Volume and Surface Resistivity of Glass Fiber Reinforced Thermoset Composites

This paper is focused on the analysis of selected dielectric parameters stability under the conditions of selected accelerated climatic aging. This stability is analyzed for glass fiber reinforced composites with different thermosetting matrix suitable for the production of electrical insulating and also construction elements. Different types of thermosetting resins (epoxy and polyurethane resins) were chosen for the preparation of composites, which are the subject of the presented experiment. Tested composites were firstly characterized in the delivered state and then after the accelerated climatic aging. Important dielectric parameters were evaluated, which are the volume resistivity and the surface resistivity. Two different tests of accelerated climatic aging were realized. The first one was Temperature/humidity cyclic test, which consists of alternated intervals (i) under the temperature of 55 °C and the humidity of 93 %RH and (ii) under the temperature of 25 °C and the humidity of 97.5 %RH. The second one was Damp heat steady state test when samples were exposed to the temperature of 85 °C and the humidity of 85 %RH continuously for 1000 hours. Based on the measured data of resistivities, prospective materials were selected for further activities leading to the production of construction elements with also good electrical insulating properties and with their minimal affection by simulated climatic conditions.