Insight Into the Space Charge Behavior of Cross‐Linked Polyethylene by Tailoring the Silane Structure

ABSTRACT The rational selection of voltage stabilizers can effectively suppress space charge accumulation and electric field distortion of HVDC systems, raise the operating voltage level, and expand the power transmission capacity. However, systematic methodologies for guiding the structural design and selection of such voltage stabilizers remain extremely limited. In this study, by tailoring the molecular structure of trimethoxy silane derivatives, XLPE masterbatch incorporating crosslinking agents, antioxidants, and silane derivatives was prepared using an adsorption method. In situ crystallization experiments demonstrated that the short‐chain trimethoxy silane (TMS‐8C) is conducive to reducing the spherulite size and the volume of amorphous regions in XLPE, thereby enhancing its breakdown strength. Density functional theory indicates that short‐chain trimethoxy silane molecules possess a large dipole moment and high electron affinity, forming deeper traps that enable them to effectively capture high‐energy electrons and negative space charges. Compared with long‐chain trimethoxy silane (TMS‐18C), short‐chain trimethoxy silane (TMS‐8C) reduces electric field distortion by 24.9% and 49.5% at 30°C and 70°C, respectively. Therefore, the selection of suitable voltage stabilizers based on electron affinity and the regulation of XLPE spherulite size constitutes an effective strategy for developing high‐performance HVDC insulation materials.