Highly insulating thermoplastic nanocomposites based on a polyolefin ternary blend for high-voltage direct current power cables

Soroudi, Azadeh; Ouyang, Yingwei; Nilsson, Fritjof; Östergren, Ida; Xu, Xiangdong; Li, Zerui; Pourrahimi, Amir Masoud; Hedenqvist, Mikael S.; Gkourmpis, Thomas; Hagstrand, P.‐O.; Müller, Christian

doi:10.1039/d1nr08255h

Cited by 8 publications

(4 citation statements)

References 45 publications

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“…With the rapid development of offshore wind power worldwide, high-voltage direct current (HVDC) cables have become the mainstay of long-distance wind power access to the grid. Currently, the most commonly used HVDC cable is an extruded cable insulated with cross-linked polyethylene (XLPE) [1][2][3][4], and the voltage level of the cable in operation has reached ± 320 kV. However, it is difficult to further raise the transmission voltage level to a higher voltage level, i.e.…”

Section: Introductionmentioning

confidence: 99%

Effects of cooling rate on space charge characteristics of polypropylene

Men,

Jiang,

Liu

et al. 2024

Phys. Scr.

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Polypropylene (PP) is considered as a candidate for ultrahigh-voltage direct current (UHVDC) cable insulation owing to its excellent thermal stability, insulation properties, and environmental friendliness. It is a semi-crystalline polymer, and the difference in cooling rate during processing affects its crystallisation morphology and characteristics, which may change its insulation properties. In this study, PP film samples with varying cooling rates of 10, 20, 40, 70, 120, and 170 ℃ min−1 were prepared. The crystal morphology was observed, crystal characteristics were analysed, and the space charge distribution and direct current (DC) breakdown strength were measured. It can be concluded that with an increase in the cooling rate, the spherulite size of PP decreased, the spherulite number increased, and the characteristic breakdown strength increased. Notably, the variation trends of the space charge distortion factor and carrier mobility of PP are opposite to that of crystallinity. When the cooling rate was 40 ℃ min−1, the number of space charges in PP was small, the distortion of the electric field was not obvious, the apparent mobility of carriers was high, the charge decay was rapid in the depolarisation process, and the average breakdown strength was acceptable. Therefore, during the processing of the UHVDC cable, the space charge characteristics of PP can be optimized by adjusting the cooling rate.

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Section: Introductionmentioning

confidence: 99%

Effects of cooling rate on space charge characteristics of polypropylene

Men,

Jiang,

Liu

et al. 2024

Phys. Scr.

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“…Strategies to improve the cable endurance involve a decrease in electrical conductivity and an improvement in the resistance to electrical breakdown. State-of-the-art polymer cable insulation is based on polyolefins that have an electrical conductivity on the order of 0.1–10 fS/m at 30 MV/m and a temperature of 60–70 °C. − To achieve these low conductivity levels, a first approach is to keep the materials clean from volatile components that could contribute as ionic charge carriers. With almost only electronic charge carriers, electrons, and holes, the strategies to further reduce conductivity are primarily to add nanoparticles or molecular additives.…”

Section: Introductionmentioning

confidence: 99%

Coarse-Grained Model for Prediction of Hole Mobility in Polyethylene

Unge,

Aspåker,

Nilsson

et al. 2023

J. Chem. Theory Comput.

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Electrical conductivity measurements of polyethylene indicate that the semicrystalline structure and morphology influence the conductivity. To include this effect in atomistic charge transport simulations, models that explicitly or implicitly take morphology into account are required. In the literature, charge transport simulations of amorphous polyethylene have been successfully performed using short oligomers to represent the polymer. However, a more realistic representation of the polymer structure is desired, requiring the development of fast and efficient charge transport algorithms that can handle large molecular systems through coarse-graining. Here, such a model for charge transport simulations in polyethylene is presented. Quantum chemistry calculations were used to define six segmentation rules on how to divide a polymer chain into shorter segments representing localized molecular orbitals. Applying the rules to amorphous systems yields distributions of segments with mode and median segment lengths relatively close to the persistence length of polyethylene. In an initial test, the segments of an amorphous polyethylene were used as hopping sites in kinetic Monte Carlo (KMC) simulations, which yielded simulated hole mobilities that were within the experimental range. The activation energy of the simulated system was lower compared to the experimental values reported in the literature. A conclusion may be that the experimental result can only be explained by a model containing chemical defects that generate deep traps.

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“…Both types of blends feature electrical conductivities that are comparable to or even less than values reported for XLPE. The dielectric properties of novel insulation materials can be tuned further through the addition of metal oxide nanoparticles, [13,14] aromatic molecules [15,16] or organic semiconductors. [17,18] An additional advantage of thermoplastic formulations is the possibility to reprocess the material by remelting, which may ease recycling of the cable insulation for other applications once a cable has reached the end of its lifetime.…”

Section: Introductionmentioning

confidence: 99%

Polyethylene Based Ionomers as High Voltage Insulation Materials

D'Auria

Pourrahimi

Favero

et al. 2023

Adv Funct Materials

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Polyethylene based ionomers are demonstrated to feature a thermo‐mechanical and dielectric property portfolio that is comparable to cross‐linked polyethylene (XLPE), which may enable the design of more sustainable high voltage direct‐current (HVDC) power cables, a crucial component of future electricity grids that seamlessly integrate renewable sources of energy. A new type of ionomer is obtained via high‐pressure/high‐temperature free radical copolymerization of ethylene in the presence of small amounts of ion‐pair comonomers comprising amine terminated methacrylates and methacrylic acid. The synthesized ionomers feature a crystallinity, melting temperature, rubber plateau modulus and thermal conductivity like XLPE but remain melt‐processable. Moreover, the preparation of the ionomers is free of byproducts, which readily yields a highly insulating material with a low dielectric loss tangent and a low direct‐current (DC) electrical conductivity of 1 to 6·10−14 S m−1 at 70 °C and an electric field of 30 kV mm−1. Evidently, the investigated ionomers represent a promising alternative to XLPE‐based high voltage insulation, which may permit to ease the production as well as end‐of‐use recycling of HVDC power cables by combining the advantages of thermoset and thermoplastic materials while avoiding the formation of byproducts.

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Highly insulating thermoplastic nanocomposites based on a polyolefin ternary blend for high-voltage direct current power cables

Abstract: Octyl-silane-coated Al2O3 nanoparticles are found to be a promising conductivity-reducing additive for thermoplastic ternary blends comprising low-density polyethylene (LDPE), isotactic polypropylene and a styrenic copolymer.

Cited by 8 publications

References 45 publications

Effects of cooling rate on space charge characteristics of polypropylene

Effects of cooling rate on space charge characteristics of polypropylene

Coarse-Grained Model for Prediction of Hole Mobility in Polyethylene

Polyethylene Based Ionomers as High Voltage Insulation Materials

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