In-Situ saxs/waxd analysis on structural evolution in peek irradiated by 1 MeV electrons during tensile deformation

Abstract

Polyether ether ketone (PEEK) is widely used as an electrical insulation material in aerospace field due to its excellent thermal and electrical properties. The changes in micro structure of the PEEK irradiated by 1 MeV electrons are studied by in-situ analysis of synchronous small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) during tensile deformation at room temperature. The tensile strength and the elongation at break of the irradiated PEEK decrease obviously, which is compared with the pristine one. The differential scanning calorimetry (DSC) analysis shows that the pristine PEEK begins to melt at 334.8 °C, the melting peak Tm appears at 339.7 °C and a deeper exothermic crystallization peak Tc appears at 297.8 °C during the cooling process. The crystallization peak temperature decreases with the increase of the irradiation fluences. The pristine PEEK has a significant scattering peak along the meridian direction of the SAXS pattern, which indicates that the crystal lamellae of the material exhibits a certain orientation, and the position of the scattering peak changes little after irradiation. The intensity of SAXS decreases with the increasing of stretching strains, and the descent rate increases with the increasing of the irradiation fluences. According to the WAXD analysis, the width at half height of the diffraction peak increases with the increasing of the stretching strain, and the peak tends to disappear during tensile deformation. The diffraction peak disappearance rate increases with the increasing of the irradiation fluences.