Electrical Property of Polypropylene Toughened by β Nucleating Agent

High-performance polymer insulating material is a crucial knob for developing HVDC power cables. However, the production process of traditional cross-linked polyethylene, especially degassing, is complicated. The space charge accumulation could render severe electric field distortion under high temperatures and electrical stresses, detrimental to the insulation reliability. As a potential alternative, polypropylene (PP) has excellent properties and is environmentally friendly. However, crucial challenges for the PP application include brittleness deficiency at low temperatures and space charge problems caused by toughened PP composites. In recent years, the β nucleating agent (β-NA) has emerged as an effective additive to improve mechanical and electrical properties due to the introduction of the β-crystal form. Herein, PP/β-NA with different contents and self-assembled β-NA were subsequently prepared, respectively. The melting and crystallization behaviors, crystalline structure, and electrical properties were systematically investigated, and the influence on the space charge characteristics of PP/β-NA composites was explored. We aim to summarize the β-crystal form regulation strategies for advanced PP materials and how they perform, point out the critical characteristic parameters to improve the target performance, and offer suggestions for the rational design for future HVDC cable engineering.