Improvement in surface degradation properties of polymer composites due to pre-processed nanometric alumina fillers

Abstract

Insulating materials in power apparatus are often exposed to surface discharges in the course of normal operation, resulting in deterioration of the material surface. In an earlier work, the authors have shown that the inclusion of nanometric particles (Al 2 O 3 ) improves the ability of a polymeric dielectric (epoxy) to resist degradation when exposed to surface discharges. In the current work, the effect of pre-processing the alumina nanoparticles before preparation of the composite, is investigated. Laser Surface Profilometry (LSP) was used to measure the degradation of the composite specimens after exposure to surface discharges. The use of a surfactant, viz. Sodium Dodecyl Sulfate (SDS) was found to be ineffective. However, the simple action of heating the nanoparticles before use, improved the resistance of the bulk composite to surface discharges. Further, the particles were functionalized using 3-glycidoxypropyltrimethoxysilane (GPS). This process greatly enhanced the ability of the nanocomposite to resist surface degradation. In fact, best results were obtained when the particles were first heated and then coated with GPS. Fourier Transform Infra-Red (FTIR) spectroscopy and other techniques were used to investigate chemical changes at the particle-epoxy interfaces. A direct correlation was observed between the improvement of the resistance of the composite to surface degradation and the ability of the pre-processed nanoparticles to form strong bonds with the neighboring epoxy. Effect of pre-processing particles of larger dimensions (platelets) was negligible compared to nanoparticles, indicating the possible importance of the interfacial surface to volume ratio of the fillers.

Modelling of the thermal conductivity in polymer nanocomposites and the impact of the interface between filler and matrix

“…The small peak at 1634 cm −1 indicates the deformation of OH groups or water molecules [56]. After surface treatment the peak corresponding to OH groups was reduced.…”

Principles and Applications of Microwave Testing for Woven and Non-Woven Carbon Fibre-Reinforced Polymer Composites: a Topical Review

“…ε ″ r in the orthogonal case is approximately half of that in the parallel case. As the epoxy resin is a polar dielectric material [23], only the dipolar relaxation exists. The lower ε ″ r of the epoxy indicates that the epoxy itself does not contribute much to the high loss of the composite, so the primary loss is due to the carbon fibres.…”

“…In the test, a microstrip line was made on a FR4 substrate, and the distance Fig. 2 Diagram of the cross section of the self-sensing sensor proposed by Todoroki [21][22][23] between the board and an impacted sample (usually called standoff distance) was 100 μm. The microwave signal was generated with a vector network analyser (VNA).…”

Partial Discharge Resistance According to Frequency Acceleration Deterioration of Epoxy/Layered Silicate Nanocomposites

“…고분자들 가령 폴리아미드(polyamide:PA) [8], 폴리에칠 렌(polyethylene:PE), 폴리프로필렌(polypropylene:PP), 에칠 렌비닐아세테이트 (ethylene vinyl acetate : EVA), 불포화폴 리에스테르 [9], 에폭시수지(epoxy resins) 그리고 실리콘고무 (silicone rubbers) 와 나노입자들 즉, 층상실리케이트 (layered silicate :LS) [10], 실리카(silica: SiO2) [11], 티타네이 트(titania:TiO2) [4], 알루미나( alumina : Al2O3) [12] 그리고 산화마그네슘(magnesia: MgO) [8], [13] [12], [17], [18]. [11].…”