Influence of silver nanowires on thermal and electrical behaviors of a poly(epoxy) coating for aeronautical application

Abstract

Thermal and electrical behaviors of a poly(epoxy) coating with high electrical conductivity used for aeronautic applications are investigated. The poly(epoxy) used is designed for resin transfer molding (RTM) applications, it have a low viscosity at room temperature (around 1 Pa s) and a high T g (>160 C). This study details the influence of silver nanowires with a high aspect ratio, on the thermal behavior such as the relative degree of reaction α and the kinetics parameters thanks to dynamic and isothermal differential scanning calorimetry. Conductivity measurements of surface and volume have permitted to determine a very low percolation threshold at around 0.7% in volume. The value of electrical conductivity above the percolation threshold is upper than 10 2 S m −1 and the lowest surface resistivity was measured around 13 mΩ sq −1 both for 8% in volume of AgNWs. This kind of coating has a great interest for lightning strike protection of aircraft parts due to the high electrical conductivity obtained with a low overweight.

Dynamic electrical and mechanical properties of epoxy/silver nanowires composites

“…For the storage modulus in the glassy state, the lower percentage of hardener induces an increase in its value between −140°C and 20°C. It is explained by a higher conversion degree near the equilibrium stoichiometry (79/21) with a higher rigidity of the network 21 . Above 100°C, the modulus decreases due to the mechanical manifestation of the glass transition.…”

“…The respective mass proportions of epoxy resin and hardener were 75/25 instead of the preconized ratio (79/21). The influence of the epoxy/amine ratio on the physical structure and the cure kinetic was investigated in a previous work 21 . For this purpose, four compositions (70/30, 75/25, 79/21, and 80/20) were prepared for the mechanical study.…”

“…The values for the chemical compositions 70/30, 75/25, 79/21, and 80/20 are respectively: 4.22 ± 0.06%, 3.86 ± 0.01%, 3.81 ± 0.06%, and 3.41 ± 0.09%. This result could be associated to a more important free volume into the matrix with an excess of hardener due to a lower relative degree of conversion 21 . The presence of free molecules of hardener, DACH and DETDA, may induce a higher water sorption because of their polarity.…”

“…The aim of this work is to study the mechanical and dielectric behaviors of conductive composites epoxy/silver nanowires (AgNWs). This composite is designed to develop a high conductive coating with low filler content 21 (≤8% in volume) and could be used as an LSP of aircrafts.…”

Innovative conductive polymer composite coating for aircrafts lightning strike protection

“…In this case, the percolation threshold is reached for a volume fraction lower than 1%vol keeping the mechanical properties and the lightweight of the polymer composites. Best results in epoxy matrix were obtained with silver nanowires which exhibit an electrical conductivity around 10 2 S m −1 for particles content lower than 5%vol.…”