Degradation of Silicone Rubber Analyzed by Instrumental Analyses and Dielectric Spectroscopy

Improvement of electrical insulation performance of silicone rubber cables due to exposure to heat and radiation

“…More information concerning the effects of heat and gamma rays on SiR, individual or combined, can be found elsewhere. [17][18][19][20][21][22][23][24]…”

“…26,27 We will discuss the measurement results while correlating them with the above findings on various characteristics of SiR. [17][18][19][20][21][22][23][24] 2 | EXPERIMENTAL METHODS…”

“…From the above backgrounds, large-scale research on the degradation processes of many cable insulation materials in environments in NPPs began around 2000 in the USA 5,6 and several countries in Europe. 7,8 In Japan, we have been carrying out various research projects, entrusted by the Secretariat of the Nuclear Regulation Authority in Japan, on XLPE, 9,10 FR-XLPE, 11,12 FR-EPDM, 13,14 FR-XLPO, 15,16 SiR, [17][18][19][20][21][22][23][24] and two kinds of epoxy resins. 3,4,25 As a result, the following findings have been obtained for sheet-shaped SiR samples.…”

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

“…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 spin–echo 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 [10–14], 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 [15–20], and ageing due to partial discharge, electrical treeing, and water treeing [21–23].…”