Reduced and Surface-Modified Graphene Oxide with Non-Linear Resistivity
(English)Manuscript (preprint) (Other academic)
Field-grading materials (FGMs) are used to reduce the probability for electrical breakdowns in critical regions of electrical components and are therefore of great importance. Usually, FGMs are heavily filled (40 vol.%) with semi-conducting and conducting particles. Here, the use of polymer-grafted reduced graphene oxide (rGO) as a filler to accomplish percolation networks is explored at very low filling ratios (<2 vol.%) in a semi-crystalline matrix (EBA). Various simulation models are used to predict the percolation threshold and the flake-to-flake distances, to complement the experimental results. A substantial increase in thermal stability of rGO is seen after surface modification, either by silanization or subsequent polymerizations. The non-linear DC resistivity of neat and silanized rGO and its trapping of charge-carriers in semi-crystalline EBA are demonstrated for the first time. It is shown that the polymer-grafted rGO improve the dispersibility in the EBA-matrix and that the graft length controls the inter-flake distances (i.e. hopping distance). By the appropriate selection of graft lengths, both highly resistive materials at 10 kV mm-1 and FGMs with large and distinct drops in resistivity (six decades) are obtained and followed by saturation. The nonlinear drop in resistivity is attributed narrow distributions of inter-flake distances of grafted rGO.
tuning of properties, non-linear resistivity, polymer-grafting, field-grading, rGO
Research subject Fibre and Polymer Science
IdentifiersURN: urn:nbn:se:kth:diva-204040OAI: oai:DiVA.org:kth-204040DiVA: diva2:1084018
FunderSweGRIDS - Swedish Centre for Smart Grids and Energy Storage
Qc 201703232017-03-232017-03-232017-03-23Bibliographically approved