Evolution of ion mobility in cured epoxy-amine system as determined by time-of-flight method

Abstract

The concept of the time-of-flight (TOF) method for the determination of ionic carriers' mobility is presented. This method is used for the model system, the properties of which (including viscosity) change with time: the isothermally cured epoxy-amine system. It is demonstrated that the form of the TOF current signals depend on the material of the electrodes. The Cu, Ag, Al, and Au electrodes were tested; of these, the Cu and Au electrodes have yielded the most distinct TOF signals and therefore were chosen for further experiments. The investigated samples were placed between parallel electrodes with guard rings distanced with polyethylene terephthalate (PET) films of different thickness (0.02-0.2 mm). According to the predictions, it was found that the TOF of the ionic carriers increases with an increase of the distance between the electrodes (for constant electric field) and decreases with an increase of the electric field (for constant distance). The series of measurements performed for the well-known epoxy resin system diglycidylether of bisphenol A with diamino-4,4dimethyl-3,3-dimethyldicyclohexylmethane, isothermally cured at different temperatures, have confirmed that in a course of the curing, below the gelation, the conductivity decreases following the decrease of the ionic mobility due to the viscosity increase during the reaction. However, with an advancement of reaction, deviations from that linear relationship are observed.

Isothermal curing of epoxy resins as seen by direct current and rheological measurements

“…The experimental details of DC measurements were published elsewhere [3,4,13,23], the basics of DMA techniques can be found in [24], whereas the backgrounds and the experimental conditions of ToF measurements in [18][19][20].…”

“…2) Université Claude Bernard Lyon l, Laboratoire des Matériaux Polymeres et des Biomatériaux "LMPB", Bâtiment "ISTIL", UMR CNRS 5627, 69622 Villeurbanne, France. *) To whom all correspondence should be addressed; e-mail: julanski@ p.lodz.pl the epoxy-amine systems under isothermal conditions by electrical techniques [18][19][20]. Our previous ion carrier mobility measurements (Time-of-Flight method -ToF) were performed in an order to verify the basic assumption of the electrical techniques that the ion conductivity is directly related to the medium viscosity [20].…”

Investigation on space charge dynamics and mechanical properties of Epoxy Alumina nanocomposites

“…Figure 10 shows the time dependent space charge profile during poling of epoxy nanocomposites under the electric field of 10 kV mm −1 . Heterocharges formation were observed in the vicinity of cathode was due to the ionization of impurities present in the epoxy and due to the presence of dominant charge carrier, typically Na+ion in the epoxy resin [20]. At 3 wt% of alumina nanofiller, large heterocharges accumulation near the cathode were observed and at 5 wt% of nanofiller decrement of heterocharges were observed, and this could be due to the neutralization phenomenon happened near the cathode.…”

Epoxy/BN micro- and submicro-composites: dielectric and thermal properties of enhanced materials for high voltage insulation systems

“…This phenomenon, along with the findings of higher dielectric losses due to conductivity at elevated temperatures and low frequencies for the neat epoxy, as well as the shift of the α-peak towards lower frequencies for the BN composites, can partially be explained by higher chain mobility in the neat epoxy as compared to the BN composites. It is further known, that free ionic species remaining from the synthesis process contribute to the increased dielectric losses in epoxy resins at high temperatures [13,[16][17][18]. Introducing BN particles in the epoxy matrix subsequently results in less mobile ionic charge carriers in the composite, leading to lower losses due to conductivity with increasing BN filler amount.…”