Eco‐friendly polypropylene power cable insulation: Present status and perspective

Abstract

Environmental protection is the future trend of power equipment development, and is also a research hotspot in the field of power cable insulation in recent years. Due to the excellent electrical properties and recyclability, polypropylene (PP) based composites are regarded as promising insulating materials for eco‐friendly next‐generation power cables. However, the high modulus and hardness of pure PP make it difficult to be directly employed as cable insulations, which needs to be further optimised. General methods of mechanical performance regulation often result in the deterioration of electrical performance, such as breakdown strength, space charge and so on. Therefore, it is recognised that the major challenge impeding practical applications of PP power cable insulation arises from the synergetic regulation of multi‐performances. The multi‐level structures influencing the multi‐performances of PP are introduced by the authors and the researches on the performance enhancement of PP through nanoscale structure regulation in recent years are reviewed in detail. Seven kinds of modification methods including nano‐doping, chemical grafting, in‐suit copolymerisation, heat treatment, nucleating agent, voltage stabiliser and elastomer blending are paid special attention. Based on the full understanding of the research status, the challenges and issues of future research are put forward for eco‐friendly PP power cable insulation.

Simultaneous Promotion of the Mechanical Flexibility and Dielectric Strength of Impact Polypropylene Copolymers Containing Multifold H-Shape Long-Chain-Branching Structures for Recyclable Power Cable Insulation Application

“…However, the LCB-IPC sample of Control_1 is still not what power cable insulation materials demand, not least when mechanical flexibility is concerned. 2 Containing 20.5 wt % of EPC and having a high elongation at break in the tensile test of 838%, the sample Control_1 is, however, still too stiff to be a power cable insulation material because of its high flexural modulus over 1000 MPa (1011.0 MPa), which is way higher than that of XLPE (∼200 MPa). 32 To further enhance the mechanical flexibility, it is obvious that ethylene needs to be continuously increased for its incorporation in LCB-IPCs.…”

“…PP, being predominantly isotactic, has a much higher melting temperature than polyethylene (PE) in general, which assures an excellent thermo-mechanical performance without the need to cross-link. Like PE, PP is also of excellent electrical properties in terms of insulation, including low dielectric constant, low dielectric loss, and high dielectric strength. , Nevertheless, it is still far from ideal for PP to be eligible as power cable insulation materials. The primary concern lies in its high mechanical rigidity, due to which the mechanical flexibility of power cables cannot be met when insulated by PP .…”

Hierarchical Structural Evolution, Electrical and Mechanical Performance of Polypropylene Containing Intrinsic Elastomers under Stretching and Annealing for Cable Insulation Applications

“…Over the past decades, great development of high-voltage power transmission technologies has been achieved to accommodate the intensely increasing demand for renewable energy and long-distance power transmission. − Extruded cables based on cross-linked polyethylene (XLPE) insulation materials have attracted extensive attention in the field of electric power delivery due to their excellent thermo-mechanical properties and electrical behavior at high temperatures. − However, there is an irreconcilable contradiction between the intrinsic thermoset features of XLPE and the increased worldwide awareness of sustainable development. , The thermoplastic polypropylene (PP) insulated cables have become an attractive alternative to substitute traditional cable insulated with XLPE, originating from a series of advantages of PP insulation, such as excellent insulation performance, high operating temperature, brilliant recyclability, fast manufacturing processing with reduced cost, and unlimited cable length without considering scorch phenomena. − Unfortunately, the brittleness at low temperatures and the lack of flexibility at room temperature for PP can hardly meet the requirement of mechanical properties for cable insulation materials. , For instance, the elastic modulus of PP is up to 1.6 GPa, while it is encouraged to be reduced to lower than 600 MPa. To address the emerging challenge, a growing body of research on PP insulation materials has been conducted to balance their thermo-mechanical and electrical performance.…”

Balancing the Strength–Impact Relationship and Other Key Properties in Polypropylene Copolymer–Natural CaSO4 (Anhydrite)-Filled Composites

“…Polypropylene (PP) is one of the most used and cheapest thermoplastics available today, with growing demands for various end-use markets (packaging, textiles, building and construction, automotive, electrical, and engineering components) [ 1 , 2 , 3 , 4 ]. Produced as PP homopolymers (PPhs) or copolymers (PPcs), PP offers a combination of outstanding physical, mechanical, thermal, and electrical properties (not encountered in other thermoplastics), excellent processability, and the possibility of recycling [ 4 , 5 , 6 ]. Moreover, adequately modified, or customized, PP is a low-cost, performant material of interest for many engineering applications, such as in the automotive industry, which is considered one of the largest PP end-use sectors.…”