In orbit, satellites are subject to three major constraints : space vacuum, electromagnetic radiation
and particle irradiation. Since the radiative space environment is responsible for almost 20% of the
anomalies observed on satellites, it is essential to know the effect of these irradiations on the materials
present in orbit [1]. This study focuses on high-energy particles, which ionize the material and can
affect its physical properties. The chosen study material is PolyEtherEtherKetone (PEEK), a semicrystalline
polymer known for its high stability to irradiation and good thermal properties. This work
focuses on the evolution of the physico-chemical structure of the polymer and its molecular mobility
with proton irradiation.

The evolution of its physical structure was followed by Differential Scanning Calorimetry (DSC). After
irradiation, the crystallinity rate decreased, as did the melting temperature. This highlights the
amorphisation phenomenon. An increase in glass transition temperature is also observed following
aging. This is commonly associated with cross-linking in polymers [2]. Irradiation creates radicals that
recombine to form bonds between macromolecules.

Molecular mobility was analysed using Dynamic Dielectric Spectroscopy (DDS). The α mode, which
is associated with the dielectric manifestation of the glass transition shifts towards higher temperatures
with the increase of dose. This result is consistent with the phenomenon of cross-linking revealed
by DSC. The evolution of the Maxwell-Wagner-Sillars (MWS) towards longer times after irradiation
is also observed. It can be explained by a difference in conductivity between the amorphous and
crystalline phases. The hypothesis is that cross-linking limits charge mobility and therefore reduces
conductivity.

[1] Aurélien Roggero, « Analyse du vieillissement d'un adhésif silicone en environnement spatial :
influence sur le comportement électrique », PhD Thesis, Université Paul Sabatier - Toulouse III, 2015.
[2] Tsuneo Sasuga et Miyuki Hagiwara, « Mechanical Relaxation of Crystalline Poly(Aryl-Ether-
Ether-Ketone) (PEEK) and Influence of Electron Beam Irradiation », Polymer, 1986, p. 821-826.