Abstract
In this paper, crosslinked polyethylene-polystyrene (XLPE-PS) composites with different degrees of crosslinking were fabricated by using different crosslinking agent contents and their direct current (DC) breakdown performance at 30~90 °C was investigated. Results show that with the increase of the degree of crosslinking, the crystallinity of XLPE-PS composites decreases gradually, but their DC breakdown strength demonstrates an increasing trend at 30~90 °C and the enhancement also increases with the rise of temperature. And as the degree of crosslinking increases, the elastic modulus of XLPE-PS composites is reduced and the loss tangent peak temperature decreases but the peak shifts to a lower value, which reveals the suppression of the relaxation process for crystallites. It is believed that high DC breakdown strength with good temperature stability for XLPE-PS composites with a larger degree of crosslinking is attributable to the presence of PS and suppression in the formation of crystallites due to crosslinking.
Highlights
Crosslinked polyethylene (XLPE) has long been favored as an insulating material for extruded high-voltage (HV) alternating-current (AC) power cable systems due to its benefits of outstanding electrical, mechanical and thermal properties [1], but in the case of direct-current (DC), with power cable systems trending towards higher voltages and a larger capacity, one of the urgently desired characteristics for polyethylene insulating materials is a high DC breakdown strength with good temperature stability [2]
Despite the phenomenon that DC breakdown strengths of all samples tend to decrease with the increase of temperature, but it could be noticed that compared with pduecrreeLasDePwEi,thDtChebirnecarkedaosewonf stetrmenpgerthatsuoref,cboumt pitocsoituelsdabree neonthicaendcethdaftrcoomm3p0arteod9w0 i°tCh.pTuhree eLnDhPaEn,cDemCebnrteaokf dDoCwbnresatrkednogwthns ostfrceonmgtphodsiitfefesrasrienetnhheacnocmedpofrsoitmes3w0 ittoh9d0if◦fCer.eTnhteDeCnhPacnocne-tmenetnst, owfhDicCh bisreqaukitdeodwifnfesrternetnfgrtohmdpifuferresXinLPthEes caosmshpoowsinteisnwFiigthurdeifSfe1roefntthDeCSPupcpolnetmenetns, twarhyicMh aisteqriuailtseadnidffereresuntltsfrformompYuraenXetLaPlE. [s1a1s].shown in Figure S1 of the Supplementary Materials and results from Yan et al [11]
The effects of the degree of crosslinking on the DC breakdown behaviors of XLPE-PS composites at 30~90 ◦C were investigated in this study
Summary
Crosslinked polyethylene (XLPE) has long been favored as an insulating material for extruded high-voltage (HV) alternating-current (AC) power cable systems due to its benefits of outstanding electrical, mechanical and thermal properties [1], but in the case of direct-current (DC), with power cable systems trending towards higher voltages and a larger capacity, one of the urgently desired characteristics for polyethylene insulating materials is a high DC breakdown strength with good temperature stability [2]. Nanofillers like MgO, Al2O3, SiO2, TiO2 and so on can improve the DC breakdown strength of polyethylene [3,4,5,6]. Based on lots of positive results acquired, nanocomposite addition is considered as one of the most promising techniques to realize the target of improving DC breakdown strength as well as related good temperature stability. It is of concern that internal stresses due to the mismatch of thermal expansion coefficients might lead to the insulation failure when a high electric field is applied [9]
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