Development of anti-static nanocomposites for the space environment

The anti-static ETFE-based nanocomposite project carried out jointly by the Luxembourg Institute of Science and Technology (LIST) in Luxembourg and Axon Cable in France recently came to a close. Funded by the European Space Agency (ESA), the project was launched in 2015 as part of an ambitious mission: to develop a new electrical wire for space applications, such as electrical cables for photovoltaic panels on satellites, making it possible to avoid electrostatic discharge phenomena related to the space environment. To meet this objective, the formulation of the wire insulation made from ethylene tetrafluoroethylene (ETFE), a high thermal performance thermoplastic polymer, was modified by adding conductive nanoparticles to dissipate the build-up of charges on the surface of the wire. This technical innovation is based on controlling electrical percolation of the nanocomposite, making it possible to produce an anti-static material with a wide range of concentration of nanoparticles. Over their three years of research, the partners have been able to update new formulations and test new prototypes of electrical wire using these nanocomposites.

An adjustable electrical percolation threshold

Researchers at LIST specialising in composite materials first discovered that the electrical percolation of ETFE nanocomposites could be mitigated by chemical treatment of the conductive nanoparticles or the matrix, and by the addition of non-conductive nanoparticles. These various methods have thus made it possible to identify anti-static formulations of ETFE. Advanced structural, thermal and mechanical testing then made it possible to validate certain electrostatic formulations for the prototyping stage.

Prototypes of electrical wire for use in space

The most promising anti-static formulations became the basis of a scale-up that has made it possible to produce prototypes of electrical wire with a design meeting ESA standards. The process conditions were optimised by Axon Cables in order to close in on the properties obtained at LIST. At the end of the project, a proposal was made to improve the current design of the electrical wire to take optimal advantage of the anti-static properties of ETFE insulation.

Custom-made testing equipment

Finally, during the project, researchers at LIST and their partners at Axon Cables have developed advanced characterisation tools for in-depth understanding of the relationships between electrical properties and structural properties at the material scale and the prototype scale.

Photo : Fabrication par extrusion de fil électrique (standard ESA ESCC3901/012 variant 4) avec isolant antistatique à base d’ETFE, à gauche : sortie de filière d’extrusion, à droite : bobinage du fil (diamètre du fil : 1 mm)