Tunable morphology and resistivity of ternary polymer composites of carbon black/low density polyethylene/ethylene‐vinyl acetate with carbon blacks having different surface properties

Abstract

Medium to extra‐high voltage electrical cables typically comprise a semiconductive polymer composite layer to homogenize the electromagnetic field through the cables. The semiconductive layers usually contain a high content of carbon black (CB) for reduced electrical resistivity. In this study, we found that both the morphology and resistivity of a ternary polymer composite of CB/low density polyethylene (LDPE)/ethylene‐vinyl acetate (EVA) depend on CBs used and the order of addition. Three types of CB were investigated. CB‐A, which has the lowest surface energy and the most uniform surface energy profile, exhibits a strong affinity to LDPE and always segregates in the LDPE phase whether it is first added in the LDPE phase or the EVA phase. CB‐B and CB‐C, which have higher and less homogeneous surface energies, distribute differently with different orders of addition. We observe a significant reduction in the percolation threshold of CB‐A in the CB/LDPE/EVA composite, but not with CB‐B or CB‐C. Adding CB‐A in the LDPE phase first results in substantially lower resistivity than adding it in the EVA phase first, whereas adding CB‐B or CB‐C in the LDPE phase first results in higher resistivity than adding them in the EVA phase first.

Performance comparison of semi‐conductive shielding layer for high‐voltage cable based on polypropylene and low density polyethylene resin

“…13 Currently, high-voltage XLPE cables usually use lowdensity polyethylene (LDPE)/ethylene vinyl acetate (EVA)/carbon black (CB) composites as their shielding materials. [14][15][16] Yu et al investigated the electrical conductivity and positive temperature coefficient effect (PTC) of LDPE/EVA/CB blended systems. 17 The results show that the resistivity of the blended system can be adjusted by double permeation and two-step permeation effects due to the addition of EVA, which effectively improves the processing and electrical properties of the composites.…”

“…Currently, high‐voltage XLPE cables usually use low‐density polyethylene (LDPE)/ethylene vinyl acetate (EVA)/carbon black (CB) composites as their shielding materials 14–16 . Yu et al investigated the electrical conductivity and positive temperature coefficient effect (PTC) of LDPE/EVA/CB blended systems 17 .…”

Effect of carbon black type and concentration on the performance of semiconductive shielding material of high‐voltage cable

“…The results showed that the higher the structure of CB the better the electrical properties of the composite. 8 Chinese scholar Yang used EVA and two types of CBs to prepare two kinds shielding materials and tested the electrical properties of the shielding materials. The results showed that when the CB concentration was the same, the shielding material with the higher structured CB had better electrical properties.…”

“…The effect of CB concentration to shielding material performance and the effect of CB type to shielding material electrical properties are more studied. [8][9][10][11][12][13][14][15] However, most of the current matrix resins for high-voltage cable shielding material are ethylene-butyl acrylate (EBA) copolymer, and there are few studies on how the type and concentration of CB affect the electrical, thermal and mechanical properties of shielding materials. Therefore, in this paper, EBA was used as the matrix resin to investigate the effect of CB type and concentration on the performance of semiconductive shielding layer.…”

“…He investigated how the type of CB affects the electrical properties of the composite. The results showed that the higher the structure of CB the better the electrical properties of the composite 8 . Chinese scholar Yang used EVA and two types of CBs to prepare two kinds shielding materials and tested the electrical properties of the shielding materials.…”