Degradation of Silicone Rubber Analyzed by Instrumental Analyses and Dielectric Spectroscopy

1 H NMR tests on damaged and undamaged XLPE and SiR samples

“…T 1 was measured using a standard saturation recovery technique, and the signal was detected by the common Hahn-echo pulse sequence. The saturation recovery technique is commonly used to measure T 1 and is very effective to obtain accurate line shapes, especially if the shape of the signal is very broad or not easily inverted [12]. The Hahn-echo pulse sequence, also called the spinecho pulse sequence, is the most common sequence applied in NMR experiments based on refocusing of spin magnetisation by a pulse of resonant electromagnetic radiation [13].…”

“…Several techniques have been employed to assess the durability and structural integrity of polymers. Amongst commonly used techniques, we cite thermal analysis techniques such as differential scanning calorimetry [9], the X-ray diffraction technique to analyse the structural changes of thermally aged XLPE, spectroscopy techniques such as Fourier-transform infrared spectroscopy method, nuclear magnetic resonance (NMR) spectroscopy and dielectric spectroscopy [10][11][12][13][14], and mechanical strength testing techniques such as elongation at break and elasticity measurements [15]. Some researchers who used NMR techniques to investigate ageing and degradation have mainly focused on thermal ageing [15][16][17][18][19][20], and ageing due to partial discharge, electrical treeing, and water treeing [21][22][23].…”