Regular Article

Experimental study of polymethyl methacrylate: damage under corona discharge

¹ Laboratoire des Technologies Avancées du Génie Electrique (LATAGE), Faculté de Génie Electrique et d'Informatique, Université Mouloud Mammeri, BP 17 RP, Tizi-Ouzou, Algeria
² Laboratoire d'Ingénierie en Sciences des Matériaux (LISM EA 4695), UFR Sciences Exactes et Naturelles, BP1039, 51687 Reims Cedex 2, France

^* e-mail: ferroudja_megherbi@yahoo.fr

Received: 23 February 2018
Received in final form: 1 June 2018
Accepted: 18 June 2018
Published online: 10 October 2018

Abstract

In high-voltage applications, insulators may be exposed to corona discharges during long periods. In this experimental work, corona discharge tests of different durations are carried out in air at atmospheric pressure on polymethyl methacrylate (PMMA) samples. The resulting surface degradation is studied with several techniques. The surface damages are observed with environmental scanning electron microscope and atomic force microscopy. The results show that electrical trees occur on the surface of material and their distribution depends on the corona discharge duration. The chemical changes on PMMA surface are analyzed by Fourier transform infrared spectroscopy and a chemical degradation mechanism is proposed. Evolution of surface resistivity with corona aging is also implemented by using a classical I(V) method. In addition, to study the dielectric behavior of PMMA, the monitoring of kinetics of the trapped charge under electron irradiation in a scanning electron microscope is performed. The charging ability of PMMA under electron irradiation and its time constant of charging decrease with electrical aging.